[git-p4] log problem

`p4 describes 114996' shows something like this:

Change 114996 by puma@injoin.injoin on 2008/06/18 12:11:24

	fix buffer overflow.

Affected files ...


//puma/Trunk/lib/string/map.c#47 edit


But `git log' shows
Author: puma <puma@p4_server>
Date:   Wed Jun 18 12:11:24 2008 +0800

    fix buffer overflow.

    [git-p4: depot-paths = "//puma/Trunk/": change = 114996]

The Author field in all logs shows puma <puma@p4_server>
All of the programmers use the perforce username 'puma' but use a different
clientspec. How can I configure git-p4 to use puma@injoin.injoin as the Author
rather than puma?

Thank you.