git-svn now reads settings even if called in subdirectory

git-svn now reads settings even if called in subdirectory

Previously, git-svn first read the .git/config file for settings as if
current working directory was the repository top-directory, and after
that made sure to cd into top-directory.  The result was a silent
failur to read configuration settings.  This patch changes the order
these two things are done.

Signed-off-by: Gustaf Hendeby <hendeby@isy.liu.se>
Acked-by: Eric Wong <normalperson@yhbt.net>