[request-tracker-maintainers] Supporting RT5 in backports requires binary packages only in backports

[Dominic Hargreaves]

Hi all

Since we missed the deadline to get RT5 into bullseye, we would like
to support this in bullseye-backports instead. The package itself
is straightforward, and we expect to migrate to bookworm with no
issues after the release.

There are also extension packages which build multiple binary names
from a single source (eg rt4-extension-foo and rt5-extension-foo). Because
we don't plan to ship RT4 in bookworm, we'd like to remove it from
unstable soon after the release. However we will need to continue to
ship RT4 extension backports, since the current RT4 extension packages are
not coinstallable with the RT5 ones.

In practice the packages are almost identical, with the extension
files being installed to the relevant versioned directories to
be picked up by the right version of RT. And on the source packaging
side, adding/removing support for major versions of RT is usually just
changing one or two variables in debian/rules (plus the debian/control
entry of course), so I would judge that as being a minimal changes that
fits the spirit of backporting.

I can't see any explicit mention of backports adding binary packages
that aren't in the testing release in
https://backports.debian.org/Contribute/, so I'm going to assume it's not
forbidden, but since it's a slightly unusual case I figured I should
raise it here in good time.

Thanks
Dominic