Bug with pull request and branches

Hello.

We're working with this private repository: https://bitbucket.org/promoru/siteindex/

And experiencing strange problems. We've made pull request from our developer's fork, https://bitbucket.org/slavootic/siteindex/, default branch, to promoru/siteindex default branch. Changes that were made in this fork were not presented in diff during pull request, and merge gave no results too.

For example, we have siteindex/extensions/jcrop/ folder now missing in our repo.
It is presented in slavootic/siteindex/ default branch here: https://bitbucket.org/slavootic/siteindex/src/039386756d2aa25e2a0db2ea76c2b9c22a5288df/extensions?at=default. And it is not presented in promoru/siteindex/ default branch: https://bitbucket.org/promoru/siteindex/src/57b7a302ba5eba3244491ce6e1b8dfdba3c36544/extensions?at=default

But when I'm trying to create Pull Request it still shows me empty diff: https://bitbucket.org/slavootic/siteindex/pull-request/new - see screenshot.

This problem is really blocking for us. Could you please explain how this happens?