git-svn: error out when the SVN connection fails during a fetch

git-svn: error out when the SVN connection fails during a fetch

finish_report does seem to return a useful value indicating success
or failure, so we'll just set a flag when close_edit is called
(it is not called on failures, nor is abort_edit) and check
the flag before proceeding.

Thanks to Pazu for pointing this out.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>