diff -r c55eac3f388d -r 56674fd6dabc mercurial/progress.py
--- a/mercurial/progress.py	Thu Jun 25 17:56:26 2015 -0500
+++ b/mercurial/progress.py	Thu Jun 25 17:56:54 2015 -0500
@@ -187,6 +187,7 @@
         delta = pos - initialpos
         if delta > 0:
             elapsed = now - self.starttimes[topic]
+            # experimental config: progress.estimate
             if elapsed > float(
                 self.ui.config('progress', 'estimate', default=2)):
                 seconds = (elapsed * (target - delta)) // delta + 1