git svn: catch lack of upstream info for dcommit earlier

Since 711521e 'git svn dcommit' attempts to use the upstream
information to determine the SVN URL, before it verifies that it even
found an upstream.  Move up the corresponding check.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Acked-by: Eric Wong <normalperson@yhbt.net>

git-svn.perl

@@ -421,15 +421,15 @@ sub cmd_dcommit {
 	$head ||= 'HEAD';
 	my @refs;
 	my ($url, $rev, $uuid, $gs) = working_head_info($head, \@refs);
+	unless ($gs) {
+		die "Unable to determine upstream SVN information from ",
+		    "$head history.\nPerhaps the repository is empty.";
+	}
 	$url = defined $_commit_url ? $_commit_url : $gs->full_url;
 	my $last_rev = $_revision if defined $_revision;
 	if ($url) {
 		print "Committing to $url ...\n";
 	}
-	unless ($gs) {
-		die "Unable to determine upstream SVN information from ",
-		    "$head history.\nPerhaps the repository is empty.";
-	}
 	my ($linear_refs, $parents) = linearize_history($gs, \@refs);
 	if ($_no_rebase && scalar(@$linear_refs) > 1) {
 		warn "Attempting to commit more than one change while ",