For Windows users the are two choices as well:
1) Set the LANG environment variable to en.
a) Overall for Windows: http://www.itechtalk.com/thread3595.html
b) For the git shell only:
If you don’t want to affect anything else except git applications you might add the following line in the beginning of C:\Program Files\Git\cmd\git.cmd file:
@set LANG=en
Please note that this will only work when launching commands from the git shell – GIT GUI launched from the start menu will not be affected
2) Delete or rename relevant *.msg file in C:\Program Files\Git\share\git-gui\lib\msgs
You save on not modifying any setup shell (especially if you use cmd.exe shells) but
you lose on international functionality.
Credits: These answers originated in the official issue raised in msysgit project which can be found here: http://code.google.com/p/msysgit/issues/detail?id=302