--- a/mercurial/graphmod.py	Sun Oct 22 22:38:16 2017 +0900
+++ b/mercurial/graphmod.py	Sun Oct 22 22:52:36 2017 +0900
@@ -48,9 +48,6 @@
     returned.
 
     """
-    if not revs:
-        return
-
     gpcache = {}
 
     for rev in revs: