goatherd.postrm: ignore if statedir is not empty

debian/goatherd.postrm

@@ -7,7 +7,7 @@ if test "$1" = "purge"; then
     statedir=/var/lib/goatherd
 
     rm -f $statedir/goatherd.sqlite3
-    rmdir $statedir || true
+    rmdir $statedir >/dev/null 2>/dev/null || true
 
     dpkg-statoverride --remove $statedir >/dev/null 2>/dev/null || true
 fi