diff -r e6b643ccf87d -r a0c3d83d5f04 mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Sat Jun 23 08:59:18 2018 +0530
+++ b/mercurial/debugcommands.py	Mon Jun 25 01:07:23 2018 +0530
@@ -427,7 +427,7 @@
         'hg debugcolor')
 def debugcolor(ui, repo, **opts):
     """show available color, effects or style"""
-    ui.write(('color mode: %s\n') % ui._colormode)
+    ui.write(('color mode: %s\n') % stringutil.pprint(ui._colormode))
     if opts.get(r'style'):
         return _debugdisplaystyle(ui)
     else: