Comment 3 for bug 571767

I got the same bug with the same traceback.

I'm 90% sure that's exactly what happened for me - accidentally changed encoding. I was scrolling up and down the file and I think my mouse went over the encoding and that's when the error popped up.

I think I've pinpointed the error:

1) Edit some files in a branch

2) Click "Diff" on the main toolbar

3) Put your mouse over the encoding and scroll up and down rapidly with the mouse wheel

4) error should pop up.

My guess as to what's happening is that when you change the encoding it tries to modify the file. And if you change the file encoding again, before it's finished modifying, it will throw the error.

A simple fix might be in whatever callback is fired on the encoding change. Just check to see if the file is locked, and then you could either discard the event and change it back to the previous encoding, or "freeze" the event until the file is no longer locked.