Code in readfile that copies over brush assets (and related data) from
the old Main to the new one cannot use the namemap reliably, due to how
the linked IDs of the library get temporarily spread between both Mains.
Since in theory there should be no need for name uniqueness processing
in this case anyway, for now disable the relevant code when the library
is re-used.
NOTE: Issue reported in #135315, revealed by recent refactor in
00f406c34c and 16e552298c.
NOTE: This fix is a bit hackish, but seems to be the simplest most
straight-forward way to address the problem. More invasive solution can
be investigated if this proves to still be problematic.
NOTE: While 4.4 also has the same invalid handling, this PR should
likely not be ported to it, as previous BKE_main_namemap code was more
permissive with such invalid behaviors, and there is no known bad
consequences in practice.
Pull Request: https://projects.blender.org/blender/blender/pulls/135362
666267ef40