> Does chrome-gnome-shell support python3?

Yes, it is support Python 3.x as well as Python 2.7.

> please update the shebangs to python3

While Python 2.7 is still supported I will not touch shebang.
Within chrome-gnome-shell sources there is distutils [1] setup.py script [2] provided (and called as part of cmake installation) that is replacing shebang in chrome-gnome-shell.py to point those Python interpreter that is used to run setup.py.

So there is should not be any problem for distros to use any wanted Python version. Just tell cmake which python interpreter to use.

[1] https://docs.python.org/3/library/distutils.html
[2] https://git.gnome.org/browse/chrome-gnome-shell/tree/connector/setup.py

Do you maintain the chrome-gnome-shell PPA?

cmake's FindPythonInterp finds python 2.7 and then goes ahead and builds for python2 even though python3 is available. That's not a problem for Debian because python2 won't be available in a clean build environment so it finds the correct version there.

Ubuntu has a bug causing python2 to be present https://bugs.debian.org/851478 I don't know if that bug will be fixed for older Ubuntu releases.

Also, I'm working on officially backporting chrome-gnome-shell 8 to older Ubuntu releases https://launchpad.net/bugs/1652537

> Do you maintain the chrome-gnome-shell PPA?

Yes, that's me

> cmake's FindPythonInterp finds python 2.7 and then goes ahead and builds
> for python2 even though python3 is available.

If there multiple Python versions are installed in build host then you should tell cmake which version you want to use.
In your case I think `-DPython_ADDITIONAL_VERSIONS=3` option should help.

> Also, I'm working on officially backporting chrome-gnome-shell 8 to
> older Ubuntu releases

Thanks for doing this! So I will obsolete PPA when this will happens.