{"action":"opened","issue":{"url":"https://api.github.com/repos/topazproject/topaz/issues/860","repository_url":"https://api.github.com/repos/topazproject/topaz","labels_url":"https://api.github.com/repos/topazproject/topaz/issues/860/labels{/name}","comments_url":"https://api.github.com/repos/topazproject/topaz/issues/860/comments","events_url":"https://api.github.com/repos/topazproject/topaz/issues/860/events","html_url":"https://github.com/topazproject/topaz/issues/860","id":134585926,"number":860,"title":"String#tr causes AssertionError","user":{"login":"mame","id":21557,"avatar_url":"https://avatars.githubusercontent.com/u/21557?v=3","gravatar_id":"","url":"https://api.github.com/users/mame","html_url":"https://github.com/mame","followers_url":"https://api.github.com/users/mame/followers","following_url":"https://api.github.com/users/mame/following{/other_user}","gists_url":"https://api.github.com/users/mame/gists{/gist_id}","starred_url":"https://api.github.com/users/mame/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mame/subscriptions","organizations_url":"https://api.github.com/users/mame/orgs","repos_url":"https://api.github.com/users/mame/repos","events_url":"https://api.github.com/users/mame/events{/privacy}","received_events_url":"https://api.github.com/users/mame/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2016-02-18T13:47:32Z","updated_at":"2016-02-18T13:47:32Z","closed_at":null,"body":"Hello,\r\n\r\n`String#tr` fails with AssertionError when the second argument is `\"=\"`.\r\n\r\n~~~~\r\n$ ~/opt/topaz/bin/topaz -v -e 'p \"x\".tr(\"x\", \"-\")'\r\ntopaz (ruby-1.9.3p125) (git rev 019daf0) [x86_64-linux]\r\nRPython traceback:\r\n  File \"topaz_objects_functionobject.c\", line 1053, in W_BuiltinFunction_call\r\n  File \"topaz_gateway_1.c\", line 54303, in method_tr\r\n  File \"topaz_objects_stringobject.c\", line 11715, in W_StringObject_method_tr\r\n  File \"topaz_objects_stringobject.c\", line 31235, in W_StringObject_tr_trans\r\n  File \"topaz_objects_stringobject.c\", line 38563, in create_trans_table\r\n  File \"topaz_objects_stringobject.c\", line 40141, in expand_trans_str\r\nFatal RPython error: AssertionError\r\nAborted (core dumped)\r\n~~~~\r\n\r\nMRI works like:\r\n\r\n~~~~\r\n$ ruby -ve 'p \"x\".tr(\"x\", \"-\")'\r\nruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-linux]\r\n\"-\"\r\n~~~~\r\n\r\nThank you,"}}