git-svn authors file in repo (Author: xxx not defined in .gitauthors file)

Hello,

We maintain a .gitauthors file for git-svn. When a new committer is added to our project, a new entry is added to the .gitauthors file, but we sometimes see errors like this:

% git -C /usr/ports svn rebase
        M       .gitauthors
r512146 = 0c1f924ca984d53333beabb909ea53afb856c44b (refs/remotes/origin/trunk)
        M       math/py-pystan/Makefile
r512147 = acc387d4c8f3ebf904010bccc5679be06b184a9d (refs/remotes/origin/trunk)
        M       deskutils/gworkspace-gwmetadata/Makefile
...
...
...
r512184 = 442bd1025776d5e3171be8e497ef2056dc47ff06 (refs/remotes/origin/trunk)
        M       www/rubygem-passenger/Makefile
        M       www/rubygem-passenger/distinfo
        D       www/rubygem-passenger/files/patch-asio-libc++7
W: -empty_dir: head/www/rubygem-passenger/files/patch-asio-libc++7
r512185 = f1a1b447811ae84011288678136e185c83180b8e (refs/remotes/origin/trunk)
        M       astro/xearth/files/freebsd.committers.markers
Author: dmgk not defined in .gitauthors file

The new committer, dmgk, was added to .gitauthors in svn commit r512146, then later he committed to the repository for the first time in r512185. It seems that if these two commits are included in the same `git svn rebase`, the error above will occur.

Is there a solution or workaround for this aside from each committer having an updated .gitauthors before doing `git svn rebase`. It's seems to be a chicken/egg issue; they first need the updated .gitauthors file, but the way to get the updated .gitauthors files is to do `git svn rebase`.

Regards,

Joseph