--- a/mercurial/debugcommands.py	Sat Jun 29 23:23:07 2019 -0400
+++ b/mercurial/debugcommands.py	Tue Jul 02 10:53:29 2019 +0200
@@ -2274,7 +2274,10 @@
     totalrawsize = datasize[2]
     datasize[2] /= numrevs
     fulltotal = fullsize[2]
-    fullsize[2] /= numfull
+    if numfull == 0:
+        fullsize[2] = 0
+    else:
+        fullsize[2] /= numfull
     semitotal = semisize[2]
     snaptotal = {}
     if numsemi > 0: