I setup a username/password authentication provider, which does not allow registration but uses the default settings otherwise. Then I was taken to the `/auth` page, where I clicked the just created provider. On the following page I was greeted with:
```
Unhandled Exception ("RuntimeException")
Undefined variable: provider
```
Versions are:
arcanist: bb8e9d7357a6417bf7231abd64f2bf33b8f8fbc2
libphutil: d7e7df98d2ea4c333e34bbd154fe8a542a335b63
phabricator: 2ff85620f0155d0b6433903d9cc9482afe84280b