File “.\picard\album.py”, line 279, in _finalize_loading
self._new_metadata.strip_whitespace()
File “.\picard\metadata.py”, line 349, in strip_whitespace
self.apply_func(lambda s: s.strip())
File “.\picard\metadata.py”, line 334, in apply_func
for key, values in self.rawitems():
RuntimeError: dictionary changed size during iteration

crashes with 2.0.4dev1 and a very simple script: $set(newartists, %artists%)

From https://community.metabrainz.org/t/picard-2-0-3-crashing-when-using-tagger-script/394671