Filesystem.Monitor: Fix NULL-dereference in bump().

Survive st being zero in bump().

Fixes [PIKE-116].

.gitattributes

@@ -7,5 +7,4 @@
 # Files containing CVS ids follow.
 # Remove the corresponding line before committing
 # changes to these files.
-/lib/modules/Filesystem.pmod/Monitor.pmod/basic.pike foreign_ident
 /lib/modules/Filesystem.pmod/Monitor.pmod/symlinks.pike foreign_ident

lib/modules/Filesystem.pmod/Monitor.pmod/basic.pike

 //
 // Basic filesystem monitor.
 //
-// $Id: basic.pike,v 1.38 2010/04/27 15:00:54 grubba Exp $
+// $Id$
 //
 // 2009-07-09 Henrik Grubbström
 //
@@ -310,7 +310,7 @@ protected class Monitor(string path,
     next_poll -= seconds || 30;
     monitor_queue->adjust(this);
 
-    if ((flags & MF_RECURSE) && st->isdir && files) {
+    if ((flags & MF_RECURSE) && st && st->isdir && files) {
       // Bump the files in the directory as well.
       foreach(files, string file) {
 	file = canonic_path(Stdio.append_path(path, file));