Problem with git shell on mac

Hi guys.

I have a problem with git on a Mac os server. a program is trying to run git shell with this command :

git shell -c git-upload-pack '/path/to/repo.git'

the process dies on an assert in exec_cmd.c :

Assertion failed: (argv0_path), function system_path, file exec_cmd.c, line 27. error: git-shell died of signal 6

what could be wrong ? is the argv0_path path to the git-upload-pack executable ? I'm pretty sure that it is in path because ssh git@server \echo $PATH contains the path to git.

What else should I do ?

Thanks for your help.