mercurial/revset.py

--- a/mercurial/revset.py	Thu Sep 22 19:40:07 2016 +0900
+++ b/mercurial/revset.py	Thu Sep 22 19:41:42 2016 +0900
@@ -913,9 +913,6 @@
     revs = None
     if 'startrev' in args:
         revs = getset(repo, fullreposet(repo), args['startrev'])
-        if not revs:
-            raise error.RepoLookupError(
-                _("%s expected at least one starting revision") % name)
     if 'file' in args:
         x = getstring(args['file'], _("%s expected a pattern") % name)
         if revs is None: