Unable to close pull request when repository has been removed (BB-7592)

Someone submitted a pull request to my project, and then subsequently closed or deleted the associated repository. Now when I click on the pull request it says "You do not have access to repository bitshifter/premake-stable-linux-findlib-fix so you cannot view the incoming changesets." and I am left with no options to close, delete, or otherwise get rid of the request.

I will contact the user and try to sort it out manually, but it would be nice if there were a button or something to drop the pull request.

If it helps, this is PR#6 on premake/premake-stable (currently at https://bitbucket.org/premake/premake-stable/pull-request/6/fixed-osfindlib-on-linux-debian)

Thanks!