(glob|magic)-deleteall does not remove existing globs/magic with xml providers

I've attached an example project. (Linux-only)

It uses xml files to define a MIME type "application/vnd.test.test".

One defines it with glob "*.foo".
The other does <glob-deleteall> and sets a glob "*.bar"

After that, the MIME database detects the MIME type vnd.test.test for both "foo.foo" and "foo.bar", but it should only detect it for "foo.bar".