git-svn: enable --minimize to simplify the config and connections

git-svn: enable --minimize to simplify the config and connections

--minimize will update the git-svn configuration to attempt to
connect to the repository root (instead of directly to the
path(s) we are tracking) in order to allow more efficient reuse
of connections (for multi-fetch and follow-parent).

Signed-off-by: Eric Wong <normalperson@yhbt.net>