MarsSeed [1] filed a deletion request for metamorphose2 [2]: This old Python2 package is not needed.
There is a Python3-based fork, currently available as a VCS package: https://aur.archlinux.org/packages/metamorphose2-python3-git [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/metamorphose2/
