mercurial/dispatch.py

--- a/mercurial/dispatch.py	Tue Sep 01 16:38:52 2015 +0900
+++ b/mercurial/dispatch.py	Mon Aug 31 23:29:15 2015 +0900
@@ -890,6 +890,8 @@
             except error.RequirementError:
                 raise
             except error.RepoError:
+                if rpath and rpath[-1]: # invalid -R path
+                    raise
                 if cmd not in commands.optionalrepo.split():
                     if (cmd in commands.inferrepo.split() and
                         args and not path): # try to infer -R from command args