git-svn: hide find_parent_branch output in double quiet mode

git-svn: hide find_parent_branch output in double quiet mode

Hide find_parent_branch logging when -qq is specified.
This eliminates more unnecessary output when run from cron, e.g.:

Found possible branch point:
http://undernet-ircu.svn.sourceforge.net/svnroot/undernet-ircu/ircu2/trunk =>
http://undernet-ircu.svn.sourceforge.net/svnroot/undernet-ircu/ircu2/branches/authz,
1919
Found branch parent: (authz) ea061d76aea985dc0208d36fa5e0b2249b698557
Following parent with do_switch
Successfully followed parent

Acked-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>