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

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