--- a/mercurial/progress.py	Sun Dec 23 22:57:03 2018 -0500
+++ b/mercurial/progress.py	Mon Dec 10 20:06:58 2018 +0000
@@ -104,6 +104,8 @@
         self.order = self.ui.configlist('progress', 'format')
         self.estimateinterval = self.ui.configwith(
             float, 'progress', 'estimateinterval')
+        # developer config: progress.debug
+        self.debug = self.ui.configbool('progress', 'debug')
 
     def show(self, now, topic, pos, item, unit, total):
         if not shouldprint(self.ui):