[matter] use copy.deepcopy with get_backtrack_infos() Portage data

A memory leak has been observed and may be related to keeping
Portage objects references alive.
[matter] initialize a dict for new_changes
Release Entropy 200
Tagging Entropy version 200
[matter] fix "changes" metadata objects handling
Release Entropy 201
Tagging Entropy version 201
Merge remote-tracking branch 'upstream/master'