--- a/hgext3rd/evolve/obsdiscovery.py	Wed Jul 17 11:45:37 2019 -0700
+++ b/hgext3rd/evolve/obsdiscovery.py	Thu Jul 11 15:30:43 2019 -0700
@@ -466,15 +466,16 @@
         repo.depthcache.update(repo)
         total = len(revs)
 
-        def progress(pos, rev):
+        def progress(pos, rev=None):
+            revstr = '' if rev is None else ('rev %d' % rev)
             compat.progress(repo.ui, 'updating obshashrange cache',
-                            pos, 'rev %s' % rev, unit='revision', total=total)
+                            pos, revstr, unit='revision', total=total)
         # warm the cache for the new revs
-        progress(0, '')
+        progress(0)
         for idx, r in enumerate(revs):
             _obshashrange(repo, (r, 0))
             progress(idx, r)
-        progress(None, '')
+        progress(None)
 
         del self._updating