git-svn: fix "Malformed network data" with svn:// servers

git-svn: fix "Malformed network data" with svn:// servers

We have a workaround for the reparent function not working
correctly on the SVN native protocol servers.  This workaround
opens a new connection (SVN::Ra object) to the new
URL/directory.

Since libsvn appears limited to only supporting one connection
at a time, this workaround invalidates the Git::SVN::Ra object
that is $self inside gs_fetch_loop_common().  So we need to
restart that connection once all the fetching is done for each
loop iteration to be able to run get_log() successfully.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>