cvsserver: Fix handling of diappeared files on update

Only send a modified response if the client sent a
"Modified" entry. This fixes the case where the
file was locally deleted on the client without
being removed from CVS. In this case the client
will only have sent the Entry for the file but nothing
else.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.de>
Acked-by: Martin Langhoff <martin@catalyst.net.nz>
Acked-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-cvsserver.perl

@@ -843,6 +843,7 @@ sub req_update
         if ( defined ( $wrev )
              and defined($meta->{revision})
              and $wrev == $meta->{revision}
+             and defined($state->{entries}{$filename}{modified_hash})
              and not exists ( $state->{opt}{C} ) )
         {
             $log->info("Tell the client the file is modified");