Comment 23 for bug 556829

(In reply to comment #21)

> On the other hand you could perhaps work around that with a hybrid approach
> whereby you get the folder from the url (rather than the existing assumption
> that it's the last folder) and removing that from the array (helpfully
> RemoveObject returns PR_TRUE only if the object was in fact in the array.)

I started off doing just that, and decided not to, for a very good reason which I'll try to remember :-)