--- a/mercurial/debugcommands.py	Sun Feb 18 15:18:07 2018 -0500
+++ b/mercurial/debugcommands.py	Sun Feb 18 15:23:26 2018 -0500
@@ -163,7 +163,7 @@
     if mergeable_file:
         linesperrev = 2
         # make a file with k lines per rev
-        initialmergedlines = [str(i) for i in xrange(0, total * linesperrev)]
+        initialmergedlines = ['%d' % i for i in xrange(0, total * linesperrev)]
         initialmergedlines.append("")
 
     tags = []