gitweb: Make use of the $git_dir variable at sub git_get_project_description

Signed-off-by: Bruno Ribas <ribas@c3sl.ufpr.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -1606,7 +1606,7 @@ sub git_get_project_description {
 	my $path = shift;
 
 	$git_dir = "$projectroot/$path";
-	open my $fd, "$projectroot/$path/description"
+	open my $fd, "$git_dir/description"
 		or return git_get_project_config('description');
 	my $descr = <$fd>;
 	close $fd;