error: unable to find <Last Commit>

Hi me and my colleagues are working on a private git repo. It seems to be broken or something.

Everytime I try to pull I get the error that

{{{
error: unable to find <Last Commit's SHA>
fatal: object <Last commit's SHA> not found
}}}

It doesn't matter which commit it is. It doesn't matter how many times my colleague push new commits. The last one always get the error on pull and the pull gets aborted.

The repo is at git@bitbucket.org:alvinteh/mfm_cheesyescapade.git

Can anyone help me out here?

I have managed to make a fork out of it. So the object is definitely there. Is there some kind config that's screwing it up?