{"abstract":"The merge base is the root commit, so merges show every change since the beginning of history.","category":"Text diff and three-way merge","checks":10,"contract":"Given a commit graph (commit -> parent list) and two commits, ancestors include the commit itself and all commits reachable through any parent. The merge bases are the common ancestors that are not ancestors of another common ancestor. Return them sorted.","contract_signature":"parents, x, y","evaluation_group":"w2-text-diff-merge-merge-base-selection","failed_approach":"Pruning only ancestors of the two tips handles fast-forwards but keeps every older common ancestor of a real fork.","family":"w2-text-diff-merge-merge-base-selection-dominance-direction","id":"FA-75626","implementations":{"attempt":{"sha256":"019c7f42bcec5d6b20c8671df91cab36d149b7cbf2822ec1abb5218f3d148ae2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(parents, x, y):\n    def anc(c):\n        seen = set()\n        stack = [c]\n        while stack:\n            k = stack.pop()\n            if k in seen:\n                continue\n            seen.add(k)\n            stack.extend(parents.get(k, []))\n        return seen\n    common = anc(x) & anc(y)\n    best = [c for c in common if not any(c != d and c in anc(d) for d in common if d in (x, y))]\n    return sorted(best)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = {\n    1: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'side': ['c1']}, 'c3', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'side': ['c1']}, 'c1', 'c2'], ['c1'])],\n    2: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'side': ['c1']}, 'c4', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'side': ['c1']}, 'c1', 'c3'], ['c1'])],\n    3: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'side': ['c1']}, 'c5', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'side': ['c1']}, 'c1', 'c4'], ['c1'])],\n    4: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'side': ['c1']}, 'c6', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'side': ['c1']}, 'c1', 'c5'], ['c1'])],\n    5: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'c7': ['c6'], 'side': ['c1']}, 'c7', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'c7': ['c6'], 'side': ['c1']}, 'c1', 'c6'], ['c1'])],\n}[N]\nfor label, args, expected in cases:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"dc03c3d279c306f1386eb43682a0479dadcdb46aa5ba083fa2fdd869cce14ff9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(parents, x, y):\n    def anc(c):\n        seen = set()\n        stack = [c]\n        while stack:\n            k = stack.pop()\n            if k in seen:\n                continue\n            seen.add(k)\n            stack.extend(parents.get(k, []))\n        return seen\n    common = anc(x) & anc(y)\n    best = [c for c in common if not any(c != d and d in anc(c) for d in common)]\n    return sorted(best)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = {\n    1: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'side': ['c1']}, 'c3', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'side': ['c1']}, 'c1', 'c2'], ['c1'])],\n    2: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'side': ['c1']}, 'c4', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'side': ['c1']}, 'c1', 'c3'], ['c1'])],\n    3: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'side': ['c1']}, 'c5', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'side': ['c1']}, 'c1', 'c4'], ['c1'])],\n    4: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'side': ['c1']}, 'c6', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'side': ['c1']}, 'c1', 'c5'], ['c1'])],\n    5: [('simple fork', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'C', 'F'], ['B']), ('merge commit sees both parents', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'E', 'F'], ['D']), ('fast-forward: one side is an ancestor', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'B', 'E'], ['B']), ('same commit', [{'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['C', 'D'], 'F': ['D']}, 'D', 'D'], ['D']), ('criss-cross has two merge bases', [{'R': [], 'X1': ['R'], 'Y1': ['R'], 'X2': ['X1', 'Y1'], 'Y2': ['Y1', 'X1']}, 'X2', 'Y2'], ['X1', 'Y1']), ('long chain against a side branch', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'c7': ['c6'], 'side': ['c1']}, 'c7', 'side'], ['c1']), ('second parent carries the only common ancestor', [{'r': [], 'a': ['r'], 'm': ['z', 'a'], 'z': [], 'b': ['a']}, 'm', 'b'], ['a']), ('unrelated histories', [{'p': [], 'q': []}, 'p', 'q'], []), ('second parent deeper in history', [{'r': [], 'a': ['r'], 'z': [], 'm': ['z', 'a'], 'top': ['m'], 'b': ['a']}, 'top', 'b'], ['a']), ('first commit is the ancestor', [{'c0': [], 'c1': ['c0'], 'c2': ['c1'], 'c3': ['c2'], 'c4': ['c3'], 'c5': ['c4'], 'c6': ['c5'], 'c7': ['c6'], 'side': ['c1']}, 'c1', 'c6'], ['c1'])],\n}[N]\nfor label, args, expected in cases:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"A deterministic, bounded teaching model of one diff, patch or merge rule with stipulated conventions; it is not a production diff or version-control implementation and makes no claim of conformance to any specific tool. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-text-diff-merge-merge-base-selection-dominance-direction","generated_at":"2026-09-29T14:49:08.608331+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A three-way merge is only as good as its base; criss-cross histories legitimately have several best common ancestors.","root_cause":"A common ancestor is discarded when another common ancestor is its ancestor, reversing the dominance test.","sha256":"b80759afc09ecb140f512cea3b2aa680a23c8a206265ba74fe832d33652754ec","title":"Merge base selection: the oldest common ancestors are kept instead of the newest · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":42.281,"exit_code":1,"observations":[{"actual":["A","B"],"check":"simple fork","expected":["B"],"passed":false},{"actual":["A","B","D"],"check":"merge commit sees both parents","expected":["D"],"passed":false},{"actual":["B"],"check":"fast-forward: one side is an ancestor","expected":["B"],"passed":true},{"actual":["D"],"check":"same commit","expected":["D"],"passed":true},{"actual":["R","X1","Y1"],"check":"criss-cross has two merge bases","expected":["X1","Y1"],"passed":false},{"actual":["c0","c1"],"check":"long chain against a side branch","expected":["c1"],"passed":false},{"actual":["a","r"],"check":"second parent carries the only common ancestor","expected":["a"],"passed":false},{"actual":[],"check":"unrelated histories","expected":[],"passed":true},{"actual":["a","r"],"check":"second parent deeper in history","expected":["a"],"passed":false},{"actual":["c1"],"check":"first commit is the ancestor","expected":["c1"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"simple fork\", \"actual\": [\"A\", \"B\"], \"expected\": [\"B\"], \"passed\": false}, {\"check\": \"merge commit sees both parents\", \"actual\": [\"A\", \"B\", \"D\"], \"expected\": [\"D\"], \"passed\": false}, {\"check\": \"fast-forward: one side is an ancestor\", \"actual\": [\"B\"], \"expected\": [\"B\"], \"passed\": true}, {\"check\": \"same commit\", \"actual\": [\"D\"], \"expected\": [\"D\"], \"passed\": true}, {\"check\": \"criss-cross has two merge bases\", \"actual\": [\"R\", \"X1\", \"Y1\"], \"expected\": [\"X1\", \"Y1\"], \"passed\": false}, {\"check\": \"long chain against a side branch\", \"actual\": [\"c0\", \"c1\"], \"expected\": [\"c1\"], \"passed\": false}, {\"check\": \"second parent carries the only common ancestor\", \"actual\": [\"a\", \"r\"], \"expected\": [\"a\"], \"passed\": false}, {\"check\": \"unrelated histories\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"second parent deeper in history\", \"actual\": [\"a\", \"r\"], \"expected\": [\"a\"], \"passed\": false}, {\"check\": \"first commit is the ancestor\", \"actual\": [\"c1\"], \"expected\": [\"c1\"], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.239,"exit_code":1,"observations":[{"actual":["A"],"check":"simple fork","expected":["B"],"passed":false},{"actual":["A"],"check":"merge commit sees both parents","expected":["D"],"passed":false},{"actual":["A"],"check":"fast-forward: one side is an ancestor","expected":["B"],"passed":false},{"actual":["A"],"check":"same commit","expected":["D"],"passed":false},{"actual":["R"],"check":"criss-cross has two merge bases","expected":["X1","Y1"],"passed":false},{"actual":["c0"],"check":"long chain against a side branch","expected":["c1"],"passed":false},{"actual":["r"],"check":"second parent carries the only common ancestor","expected":["a"],"passed":false},{"actual":[],"check":"unrelated histories","expected":[],"passed":true},{"actual":["r"],"check":"second parent deeper in history","expected":["a"],"passed":false},{"actual":["c0"],"check":"first commit is the ancestor","expected":["c1"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"simple fork\", \"actual\": [\"A\"], \"expected\": [\"B\"], \"passed\": false}, {\"check\": \"merge commit sees both parents\", \"actual\": [\"A\"], \"expected\": [\"D\"], \"passed\": false}, {\"check\": \"fast-forward: one side is an ancestor\", \"actual\": [\"A\"], \"expected\": [\"B\"], \"passed\": false}, {\"check\": \"same commit\", \"actual\": [\"A\"], \"expected\": [\"D\"], \"passed\": false}, {\"check\": \"criss-cross has two merge bases\", \"actual\": [\"R\"], \"expected\": [\"X1\", \"Y1\"], \"passed\": false}, {\"check\": \"long chain against a side branch\", \"actual\": [\"c0\"], \"expected\": [\"c1\"], \"passed\": false}, {\"check\": \"second parent carries the only common ancestor\", \"actual\": [\"r\"], \"expected\": [\"a\"], \"passed\": false}, {\"check\": \"unrelated histories\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"second parent deeper in history\", \"actual\": [\"r\"], \"expected\": [\"a\"], \"passed\": false}, {\"check\": \"first commit is the ancestor\", \"actual\": [\"c0\"], \"expected\": [\"c1\"], \"passed\": false}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}