Since fetch reforks itself at most every 1000 revisions, we
need to update the counter in the parent process to have a
working count if we set our repack interval to be > ~1000
revisions. multi-fetch has always done this correctly
because of an extra process; now fetch uses the extra process;
as well.
While we're at it, only compile the $sha1 regex that checks for
repacking once.
Signed-off-by: Eric Wong <normalperson@yhbt.net> Signed-off-by: Junio C Hamano <junkio@cox.net>