Bug: "git-svn fetch" segfaults on unknown user

Hi,

I noticed the following bug in git-svn version 1.6.0.3 (svn 1.5.5):

"git-svn fetch" segfaults if I provide an incomplete svn.authorsfile config
file setting with account<-->email mappings. This happens if an unknown user
account is found in the Subversion log.

If I do not provide svn.authorsfile at all, it doesn't crash.

Jens