Comment 0 for bug 1905634

[Impact]
Currently sbuild-launchpad-chroot fails to build/run in bionic because of bug 1892879, where a backport of ubuntu-dev-tools to bionic accidentally dropped the python2 bindings this package uses. Since this package has been collaterally damaged for months, I propose that we use the same justification used for bug 1892879 and go ahead and update s-b-c to a newer upstream that works with the python3 bindings. Specifically, I suggest we backport the version from groovy to focal and bionic. (The version in hirsute has only non-functional differences that would require extra backporting).

Other than moving to python3, all other changes to the source are fixes that have already been SRU'd back to bionic (bug 1872163, bug 1852677, bug 1858458), except for the addition of Vcs tags to debian/control.

[Test Case]
Test out all 3 commands on all supported releases:
for rel in xenial bionic focal groovy hirsute; do
  sbuild-launchpad-chroot create -n ${rel} -s ${rel} -a $(dpkg --print-architecture)
  sbuild-launchpad-chroot update -n ${rel}
  sbuild-launchpad-chroot remove -n ${rel}
done

[Where Problems May Occur]
It's possible there are some different behaviors in the underlying python2/python3 behavior that could cause an unexpected difference. I did check that downloading via proxy still works fine - but perhaps there are other such issues I didn't think to check.