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

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

[李祐棠]

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Dear git developers:

Allow me to describe the testing situation more detail:

First the testing repository is in 
https://github.com/gawel/pyquery
my git version is 1.9.2 running on Archlinux 3.14.2

I try to track issue #74(which is closed now)
It give result False/True in version 1.2.8(good), and result False/False in version 1.2.9(bad).

The testing script are manualscript.py and autoscript.py
Both of them implement the test case describe in issue #74.
Th only difference is that autoscript.py call sys.exit() to return the testing value.

First we test with git-bisect manually with manualscript.py:
The testing result is shown in 'bisectmanual_manualscript'

Then we test with git-bisect manually with autoscript.py
This time we echo $? every time we execute autoscript.py, and the testing result is shown in 'bisectmanual_autoscript'

In both situation the script give the same result, and the return value of autoscript.py is correct, too.

However, if we use git-bisect-run with autoscript.py, it will show a different result. The testing result is shown in 'bisectrun'.
The log shows that autoscript.py output False/False all the way.
As Mr. Couder said, there is some checkout commit that autoscript.py and manualscript.py give different result, for example commit d22159bb32510e9eacf6c5c2408a79792e99fe76.
If I checkout this commit outside bisect state and run manualscript.py and autoscript.py, they both give False/True result.  
So, I guess there is some problem in the checkout procedure in bisect-run, so the commit didn't successfully checkout.

ps. I found this time the bisect run give me another version of output compared to the last version I sent to everybody OAO. That is weird.

Thank for helping.
Sincerely 
YodaLee
20140828

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

[Christian Couder]

Hi,

On Thu, Aug 28, 2014 at 3:49 AM, 李祐棠 <r01942008@ntu.edu.tw> wrote:
> Dear git developers:
>
> Allow me to describe the testing situation more detail:
>
> First the testing repository is in
> https://github.com/gawel/pyquery
> my git version is 1.9.2 running on Archlinux 3.14.2
>
> I try to track issue #74(which is closed now)
> It give result False/True in version 1.2.8(good), and result False/False in version 1.2.9(bad).
>
> The testing script are manualscript.py and autoscript.py
> Both of them implement the test case describe in issue #74.
> Th only difference is that autoscript.py call sys.exit() to return the testing value.
>
> First we test with git-bisect manually with manualscript.py:
> The testing result is shown in 'bisectmanual_manualscript'
>
> Then we test with git-bisect manually with autoscript.py
> This time we echo $? every time we execute autoscript.py, and the testing result is shown in 'bisectmanual_autoscript'
>
> In both situation the script give the same result, and the return value of autoscript.py is correct, too.
>
> However, if we use git-bisect-run with autoscript.py, it will show a different result. The testing result is shown in 'bisectrun'.
> The log shows that autoscript.py output False/False all the way.
> As Mr. Couder said, there is some checkout commit that autoscript.py and manualscript.py give different result, for example commit d22159bb32510e9eacf6c5c2408a79792e99fe76.
> If I checkout this commit outside bisect state and run manualscript.py and autoscript.py, they both give False/True result.
> So, I guess there is some problem in the checkout procedure in bisect-run, so the commit didn't successfully checkout.

I don't think so.

I tried to run the following command many times in a row:

for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; python
-m pyquery.autoscript; done

And here is the log:

$ for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; python
-m pyquery.autoscript; done
Note: checking out 'bc1b16509cec70de7a32354026443fca777f4d7d'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b new_branch_name

HEAD is now at bc1b165... created a .gitignore file(which is almost a
copy of .hgignore with some minor changes and comments)
False
False
Previous HEAD position was bc1b165... created a .gitignore file(which
is almost a copy of .hgignore with some minor changes and comments)
HEAD is now at b81a9e8... fixed issue #9
False
False
Previous HEAD position was b81a9e8... fixed issue #9
HEAD is now at d22159b... test pseudo classes; documentation effort
False
True
$ for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; python
-m pyquery.autoscript; done
Previous HEAD position was d22159b... test pseudo classes; documentation effort
HEAD is now at bc1b165... created a .gitignore file(which is almost a
copy of .hgignore with some minor changes and comments)
False
False
Previous HEAD position was bc1b165... created a .gitignore file(which
is almost a copy of .hgignore with some minor changes and comments)
HEAD is now at b81a9e8... fixed issue #9
False
False
Previous HEAD position was b81a9e8... fixed issue #9
HEAD is now at d22159b... test pseudo classes; documentation effort
False
True
$ for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; python
-m pyquery.autoscript; done
Previous HEAD position was d22159b... test pseudo classes; documentation effort
HEAD is now at bc1b165... created a .gitignore file(which is almost a
copy of .hgignore with some minor changes and comments)
False
False
Previous HEAD position was bc1b165... created a .gitignore file(which
is almost a copy of .hgignore with some minor changes and comments)
HEAD is now at b81a9e8... fixed issue #9
False
False
Previous HEAD position was b81a9e8... fixed issue #9
HEAD is now at d22159b... test pseudo classes; documentation effort
False
False
$ for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; python
-m pyquery.autoscript; done
Previous HEAD position was d22159b... test pseudo classes; documentation effort
HEAD is now at bc1b165... created a .gitignore file(which is almost a
copy of .hgignore with some minor changes and comments)
False
False
Previous HEAD position was bc1b165... created a .gitignore file(which
is almost a copy of .hgignore with some minor changes and comments)
HEAD is now at b81a9e8... fixed issue #9
False
False
Previous HEAD position was b81a9e8... fixed issue #9
HEAD is now at d22159b... test pseudo classes; documentation effort
False
True
$ for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; python
-m pyquery.autoscript; done
Previous HEAD position was d22159b... test pseudo classes; documentation effort
HEAD is now at bc1b165... created a .gitignore file(which is almost a
copy of .hgignore with some minor changes and comments)
False
False
Previous HEAD position was bc1b165... created a .gitignore file(which
is almost a copy of .hgignore with some minor changes and comments)
HEAD is now at b81a9e8... fixed issue #9
False
False
Previous HEAD position was b81a9e8... fixed issue #9
HEAD is now at d22159b... test pseudo classes; documentation effort
False
False

As you can see the result of running the autoscript.py on commit
d22159b is sometimes "False False" and sometimes "False True".

Bisecting cannot work properly if the result is not stable.

> ps. I found this time the bisect run give me another version of output compared to the last version I sent to everybody OAO. That is weird.

Yeah but I doubt it is a git bisect problem or a git checkout problem.

It looks like it is a cleanup problem, because it looks much more stable with:

for rev in bc1b16509cec70de7a32354026443fca777f4d7d
b81a9e8a2b0d48ec0c64d6de14293dd4a680a20b
d22159bb32510e9eacf6c5c2408a79792e99fe76; do git checkout $rev; git
clean -dfx; cp ../testresult/autoscript.py pyquery/; python -m
pyquery.autoscript; done

Best,
Christian.