t1300-repo-config.sh failed on CYGWIN

If I run it on CYGWIN, there's an error msg:

* FAIL 39: rename section
        git-repo-config --rename-section branch.eins branch.zwei
* FAIL 40: rename succeeded
        diff -u expect .git/config
...

I run some commands...

$ cd t/trash
$ rm -f .git/config.lock
$ ../../git-repo-config.exe --rename-section branch.eins branch.zwei
error: Cannot commit config file!

Thanks,
namsh