* hash.c (rb_hash_transform_keys_bang): support key swapping in Hash#transform_keys! [Bug #14380] [ruby-core:84951] * test/ruby/test_hash.rb (test_transform_keys_bang): add assertions for this change git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62042 b2dd03c8-39d4-4d8f-98ff-823fe69b080e