Request #35660 has been Rejected by MarsSeed [1]:
Revoking. This is confusing, but seems the -py3 package was just
a fork of upstream to add some Arch Linux specific configs, but
that repo has been discontinued and archived on GitHub.
[1] https://aur.archlinux.org/account/MarsSeed/
MarsSeed [1] filed a deletion request for ros-build-tools [2]:
This Python 2 based tool is not needed anymore,
as there is a ros-build-tools-py3 package providing the same
package name as this one.
The 'Robot Operating System' supports Python 3.8+ so
there is no reason to keep their Python 2 modu
