'responsible' URL parameter filter no longer works with username

The results page actually displays the proper "assignee" in quotes, so it resolves it properly, but the list shows 0 issues.

E.g. https://bitbucket.org/site/master/issues?responsible=awbb

instead of ugly GUID-looking thing:

https://bitbucket.org/site/master/issues?responsible=557057%3A7250f3ea-2983-4778-a8cd-e1e2fe1d17ae

This used to work yesterday. A lot of people have these URLs bookmarked and considering it's actually resolves assignee I consider it bug.