commit 112f799666bac1bdbb320840d5fda3132255eb5e
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Tue Mar 06 10:23:48 2018 -0800
committer GitHub <noreply@github.com> Tue Mar 06 10:23:48 2018 -0800
tree 77b80d306834ea2ce3ed21f8ee09f7d7152c9164
parent 5a0c3987abd6a71b4fadeb525477eb5f560e8514

bpo-33009: Fix inspect.signature() for single-parameter partialmethods. (GH-6004)

(cherry picked from commit 8a387219bdfb6ee34928d6168ac42ca559f11c9a)

Co-authored-by: Yury Selivanov <yury@magic.io>

Lib/inspect.py

diff --git a/Lib/inspect.py b/Lib/inspect.py
index d629689..f271992 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -2254,7 +2254,8 @@
                 return sig
             else:
                 sig_params = tuple(sig.parameters.values())
-                assert first_wrapped_param is not sig_params[0]
+                assert (not sig_params or
+                        first_wrapped_param is not sig_params[0])
                 new_params = (first_wrapped_param,) + sig_params
                 return sig.replace(parameters=new_params)