This fixes _getMaskAtom to work correctly with the repo atoms that are
generated by MaskManager, solving the issue reported here:
https://github.com/cschwan/sage-on-gentoo/issues/90#issuecomment-
2324953
# We really only need to cache the metadata that's necessary for visibility
# filtering. Anything else can be discarded to reduce memory consumption.
portdb._aux_cache_keys.clear()
-portdb._aux_cache_keys.update(["EAPI", "IUSE", "KEYWORDS", "SLOT"])
+portdb._aux_cache_keys.update(["EAPI", "IUSE", "KEYWORDS", "repository", "SLOT"])
reposplit = myreporoot.split(os.path.sep)
repolevel = len(reposplit)