remove broken refloc

Hi,

a huge problem, as I don't need that ref anyway. But 'git gc' no longer works and that results in frequent errors when updating:

$ git gc error: cannot lock ref 'refs/remotes/release_7.5.' error: failed to run reflog

As far as I understand I could expire that ref, but that fails as well:

$ git reflog expire --expire=0 --all error: cannot lock ref 'refs/remotes/release_7.5.'

Is there a way to forcefully remove that broken ref?

Then I may be able to stop git-svn from re-importing that using the config, I hope.

Thanks,

Tobias