Hello,
I found a puzzling behavior with git-bisect for which I was unable to find any explanation. Since this might be a bug, I report it here.
cheers Christoph
What did you do before the bug happened? (Steps to reproduce your issue)
While bisecting a regression caused by a backwards-incompatible change in the sympy project, I noticed that “git bisect” can behave differently when started in different but supposedly equivalent ways.
The following complete log demonstrates the issue.
For the first run, I clone the “sympy” repository and start bisect with “git bisect start” (as shown in the first example of the git bisect manpage). I declare a good and a bad commit and am asked to estimate a specific commit. I declare this one to be good (which it is for my particular problem), but this causes git to remark that a commit is “both good and bad”.
For the second run, I provide the bad and the good commit to git-bisect start right away. I am asked to examine the same commit as before to which I give the same assessment. This time, git-bisect accepts this.
# Preparation /tmp% git clone https://github.com/sympy/sympy.git Cloning into 'sympy'... (...) /tmp% cd sympy /tmp/sympy% git checkout sympy-1.7.1 Note: switching to 'sympy-1.7.1'. (...) HEAD is now at 9e8f62e059 Merge pull request #20592 from oscarbenjamin/pr_latex_filename
# First run /tmp/sympy% git bisect start /tmp/sympy% git bisect good /tmp/sympy% git bisect bad sympy-1.10.1 Bisecting: a merge base must be tested [da03c3227771953b0dd175b5b2ef65ebb937b0df] Merge pull request #20228 from sidhu1012/perf /tmp/sympy% git describe sympy-1.6-2010-gda03c32277 /tmp/sympy% git bisect good f5bba2a7147ef8a6980ff043e93dd038c14bb9bc was both good and bad
# Second run /tmp/sympy% git bisect reset Previous HEAD position was da03c32277 Merge pull request #20228 from sidhu1012/perf HEAD is now at 9e8f62e059 Merge pull request #20592 from oscarbenjamin/pr_latex_filename /tmp/sympy% git bisect start sympy-1.10.1 sympy-1.7.1 Bisecting: a merge base must be tested [da03c3227771953b0dd175b5b2ef65ebb937b0df] Merge pull request #20228 from sidhu1012/perf /tmp/sympy% git describe sympy-1.6-2010-gda03c32277 /tmp/sympy% git bisect good Bisecting: 2606 revisions left to test after this (roughly 11 steps) [b335cf582f4a789b725cc37822d6eed42c8d9e71] add test and fix space
What did you expect to happen? (Expected behavior)
I expected git-bisect to behave in the same way both times.
What happened instead? (Actual behavior)
One time it complains that a commit is “both good and bad”, one time it does not.
Anything else you want to add:
I could not find any explanation for the difference. If it is intentional I suggest documenting it more clearly.
[System Info] git version: git version 2.30.2 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Linux 5.10.0-13-amd64 #1 SMP Debian 5.10.106-1 (2022-03-17) x86_64 compiler info: gnuc: 10.2 libc info: glibc: 2.31 $SHELL (typically, interactive shell): /bin/zsh
[Enabled Hooks]
