progress: add a changedelay to prevent parallel topics from flapping (issue2698) When combined with the earlier change to make the progress object truly a singleton, this prevents the progress bar swapping on 'hg clone --pull' on a local filesystem. Thanks to timeless for lots of debugging help at the Copenhagen sprint to isolate the root cause of this and a first draft an idea that would fix it.

--- a/tests/test-convert-svn-move.t	Thu Jun 23 14:55:09 2011 -0500
+++ b/tests/test-convert-svn-move.t	Thu Jun 23 15:00:45 2011 -0500
@@ -167,6 +167,7 @@
   > [progress]
   > assume-tty = 1
   > delay = 0
+  > changedelay = 0
   > format = topic bar number
   > refresh = 0
   > width = 60