Examine kw-only args for mutable defaults

bugbear.py

@@ -239,7 +239,7 @@ def check_for_b005(self, node):
         self.errors.append(B005(node.lineno, node.col_offset))
 
     def check_for_b006(self, node):
-        for default in node.args.defaults:
+        for default in node.args.defaults + node.args.kw_defaults:
             if isinstance(default, B006.mutable_literals):
                 self.errors.append(B006(default.lineno, default.col_offset))
             elif isinstance(default, ast.Call):

tests/b006_b008.py

@@ -42,3 +42,9 @@ def in_fact_all_calls_are_wrong(value=time.time()):
 def do_this_instead_of_calls_in_defaults(logger=LOGGER):
     # That makes it more obvious that this one value is reused.
     ...
+
+def kwonlyargs_immutable(*, value=()):
+    ...
+
+def kwonlyargs_mutable(*, value=[]):
+    ...

tests/test_bugbear.py

@@ -84,6 +84,7 @@ def test_b006_b008(self):
                 B006(22, 19),
                 B006(26, 31),
                 B008(35, 38),
+                B006(49, 32),
             ),
         )