python: Fix lambdas after certain characters not working correctly

Author: davidshepherd7

electric-operator.el

@@ -862,8 +862,9 @@ Also handles C++ lambda capture by reference."
 
 (defun electric-operator-python-mode-in-lambda-args? ()
   "Are we inside the arguments statement of a lambda?"
-  ;; \\(\\s-\\|^\\) instead of just \\b because otherwise foo_lambda matches
-  (electric-operator-looking-back-locally "\\(\\s-\\|^\\)lambda\\s-[^:]*"))
+  ;; We can't just \\b because otherwise foo_lambda matches, so we need a whole
+  ;; explicit list of things that could be before a lambda.
+  (electric-operator-looking-back-locally "\\([(,:[{=\\s-]\\|^\\)lambda\\s-[^:]*"))
 
 (defun electric-operator-python-mode-: ()
   "Handle python dict assignment"

features/python-mode.feature

@@ -176,6 +176,11 @@ Feature: Python mode basics
     When I type "lambda: x, y=1"
     Then I should see "lambda: x, y = 1"
 
+  Scenario: Space after lambda arguments even inside a function
+    When I type "foo(lambda x:x"
+    Then I should see "foo(lambda x: x"
+
+
   # Slice operator
   Scenario: Don't space : inside slices
     When I type "a[1:2]"