这是一个很久以前但未解决的问题。我决定进行调查，并发现我可以证明Git的行为与问题所述不同。一种解释是Git改进了bisect算法，或者提问者在标记提交时犯了错误。
我正在尝试学习更多关于git bisect，但在这个历史记录中遇到麻烦。我知道107ca95是好的，而3830e61是坏的。当我运行一个git bisect时，提交107ca95..3e667f8将被忽略。我碰巧知道43a07b1是引入回归的提交，但它从未被评估过。
我编写了一些代码来检查它是否被评估。我的测试表明它被评估了。运行下面的代码并验证是否出现消息为Add menu styles.的提交。
进一步的评论：
- "提交
107ca95..3e667f8将被忽略"：请注意，你标记为“好”的提交不会被评估，因为Git已经知道它是好的。
- 请阅读Christian Couder的这篇文章中的“二分算法”部分。还有“检查合并基础”部分可能与此相关。
- 如上所述，问题肯定使用不同于我使用的版本（问题来自2013年，Git 2.11来自2016年）。
Bisect运行输出
- 请注意，首先检查了“Add Admin notice”（第4行），因为它提供了最多的信息。（从上面提到的文章中阅读“检查合并基础”部分。）
- 然后，它像预期的那样分割线性历史记录。
git bisect start 'd7761d6f146eaca1d886f793ced4315539326866' 'f555d9063a25a20a6ec7c3b0c0504ffe0a997e98'
git bisect good 1b3b7f4952732fec0c68a37d5f313d6f4219e4ae
git bisect bad f9a65fe9e6cde4358e5b8ef7569332abfb07675e
git bisect bad 165b8a6e5137c40ce8b90911e59d7ec8eec30f46
代码
使用Python 3运行，带有Git 2.11.0。
运行命令：python3 script.py
""" The following code creates a git repository in '/tmp/git-repo' and populates
it with the following commit graph. Each commit has a test.sh which can be used
as input to a git-bisect-run.
The code then tries to find the breaking change automatically.
And prints out the git bisect log.
Written in response to https://dev59.com/xWQm5IYBdhLWcg3w4CIN
to test the claim that '107ca95..3e667f8 are never checked out'.
Needs Python 3!
"""
from itertools import chain
import os.path
import os
import sh
repo = {
0x3830e61: {'message': "Add data escaping.", 'parents': [ 0x0f5e148 ], 'test': False} ,
0x0f5e148: {'message': "Improve function for getting page template.", 'parents': [ 0xaaf8dc5], 'test': False},
0xaaf8dc5: {'message': "Merge branch 'navigation'", 'parents': [ 0x3e667f8, 0xea3d736], 'test': False},
0x3e667f8: {'message': "Add icons.", 'parents': [ 0x43a07b1], 'test': False},
0x43a07b1: {'message': "Add menu styles.", 'parents': [ 0x107ca95], 'test': False} ,
0x107ca95: {'message': "Add Responsive Nav.", 'parents': [ 0xf52cc34], 'test': True},
0xea3d736: {'message': "Add ‘Admin’ notice.", 'parents': [ 0x17ca0bb], 'test': True},
0x17ca0bb: {'message': "Update placeholder text.", 'parents': [ 0xf52cc34], 'test': True},
0xf52cc34: {'message': "Add featured image.", 'parents': [ 0x2abd954], 'test': True},
0x2abd954: {'message': "Style placeholders.", 'parents': [], 'test': True},
}
bad = 0x3830e61
good = 0x107ca95
def generate_queue(_dag, parents):
for prev in parents:
yield prev
yield from generate_queue(_dag, _dag[prev]['parents'])
def make_queue(_dag, inits):
""" Converts repo (a DAG) into a queue """
q = list(generate_queue(_dag, inits))
q.reverse()
seen = set()
r = [x for x in q if not (x in seen or seen.add(x))]
return r
if __name__ == '__main__':
pwd = '/tmp/git-repo'
sh.rm('-r', pwd)
sh.mkdir('-p', pwd)
g = sh.git.bake(_cwd=pwd)
g.init()
parents = set(chain.from_iterable((repo[c]['parents'] for c in repo)))
commits = set(repo)
inits = list(commits - parents)
queue = make_queue(repo, inits)
assert len(queue) == len(repo), "queue {} vs repo {}".format(len(queue), len(repo))
commit_ids = {}
for c in queue:
parents = repo[c]['parents']
if len(parents) > 0:
g.checkout(commit_ids[parents[0]])
if len(parents) > 1:
if len(parents) > 2: raise NotImplementedError('Octopus merges not support yet.')
g.merge('--no-commit', '-s', 'ours', commit_ids[parents[1]])
with open(os.path.join(pwd, 'test.sh'), 'w') as f:
f.write('exit {:d}\n'.format(0 if repo[c]['test'] else 1))
os.chmod(os.path.join(pwd, 'test.sh'), 0o0755)
with open(os.path.join(pwd, 'message'), 'w') as f:
f.write(repo[c]['message'])
g.add('test.sh', 'message')
g.commit('-m', '{msg} ({test})'.format(msg=repo[c]['message'], test='Good' if repo[c]['test'] else 'Bad'))
commit_ids[c] = g('rev-parse', 'HEAD').strip()
g.bisect('start', commit_ids[bad], commit_ids[good])
g.bisect('run', './test.sh')
print(g.bisect('log'))
