Git Bug Report: bisect run failed to locate the right commit

Git Bug Report: bisect run failed to locate the right commit

[李祐棠]

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Dear Git developers:

I just found a suspicious bug that might cause by git-bisect run. 

Version:
The git version is 1.9.2, running on Archlinux 3.14.2

The step to produce the error:
Here is the repository I participate: 
https://github.com/gawel/pyquery

It got a issue #74, that gives a wrong result in version 1.2.8
and this is fixed in 1.2.9

Here is the manual test script I use is "manualscript.py":

I use git bisect manually, search from 1.2.9(bad) to 1.2.8(good), I locate the commit that fixes this issue. The running log is attached in this file(manual).

However if I use the automatic script
git bisect run
with the script "auto script":

It will give a wrong answer, the log file is also attached(auto)

I wonder there might be some bugs in "bisect run", that give the different result. The bisect run give the wrong result, and manually there is no error in bisect

The test step is a little complicated, and I have to compress the test script and result in tar since mail server think the test code as spam. it's very sorry to bother you.

Sincerely 
YodaLee 

20140827

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Re: Git Bug Report: bisect run failed to locate the right commit

[Christian Couder]

Hi,

On Wed, Aug 27, 2014 at 3:42 PM, 李祐棠 <r01942008@ntu.edu.tw> wrote:
> Dear Git developers:
>
> I just found a suspicious bug that might cause by git-bisect run.
>
> Version:
> The git version is 1.9.2, running on Archlinux 3.14.2
>
> The step to produce the error:
> Here is the repository I participate:
> https://github.com/gawel/pyquery
>
> It got a issue #74, that gives a wrong result in version 1.2.8
> and this is fixed in 1.2.9
>
> Here is the manual test script I use is "manualscript.py":
>
> I use git bisect manually, search from 1.2.9(bad) to 1.2.8(good), I locate the commit that fixes this issue. The running log is attached in this file(manual).
>
> However if I use the automatic script
> git bisect run
> with the script "auto script":
>
> It will give a wrong answer, the log file is also attached(auto)

Your "manual" log contains:

Bisecting: 0 revisions left to test after this (roughly 1 step)
[300cd0822505a4bd308acd1520ff3ef0f20f8635] fixed issue #19
$ ./manualscript.py
False
False

While your "auto" log contains:

Bisecting: 0 revisions left to test after this (roughly 1 step)
[300cd0822505a4bd308acd1520ff3ef0f20f8635] fixed issue #19
running ./autoscript.py
False
True

So for the commit 300cd0822505a4bd308acd1520ff3ef0f20f8635 it looks
like your manualscript.py and your autoscript.py don't return the same
result.

Could you check that by doing something like:

$ git checkout -b testscripts 300cd0822505a4bd308acd1520ff3ef0f20f8635
$ ./manualscript.py
$ echo "manualscript.py exit code: $?"
$ ./autoscript.py
$ echo "autoscript.py exit code: $?"

?

By the way you can get a better bisect log by running "git bisect log"
after your bisection.

Best,
Christian.

Re: Git Bug Report: bisect run failed to locate the right commit

[Jeff King]

On Wed, Aug 27, 2014 at 01:42:45PM +0000, 李祐棠 wrote:

> Here is the manual test script I use is "manualscript.py":
> 
> I use git bisect manually, search from 1.2.9(bad) to 1.2.8(good), I
> locate the commit that fixes this issue. The running log is attached
> in this file(manual).
> 
> However if I use the automatic script git bisect run with the script
> "auto script":
> 
> It will give a wrong answer, the log file is also attached(auto)

When you get to 300cd08225, your manual bisect shows this as bad:

  Bisecting: 0 revisions left to test after this (roughly 1 step)
  [300cd0822505a4bd308acd1520ff3ef0f20f8635] fixed issue #19
  $ ./manualscript.py 
  False
  False
  $ git bisect bad

When you hit the same commit with your automatic test, the output from
your script is different:

  Bisecting: 0 revisions left to test after this (roughly 1 step)
  [300cd0822505a4bd308acd1520ff3ef0f20f8635] fixed issue #19
  running ./autoscript.py
  False
  True

which would yield "git bisect good" according to the simplified scripts
you sent. I suspect your problem is in the test script.

-Peff