CI - how to handle deps in $stablerelease

[Harald Sitter]

alohas,

so...
We now have utopic and vivid and from a CI POV we want to support at
least $lateststable and $dev series for different reasons.
Now that raises the question of what to do with build dependencies
that can not be met in $lateststable and are not actually required.

e.g.:
kwin optionally depends on libinput (0.5) for wayland input handling.
But since we presently have no interest in wayland for utopic it would
seem a bit pointless to backport a newer libinput just to satisfy the
dep.

Two obvious options present:

a) Optional dependencies we willingly do not want to address are
defined as '$dep | ci-null'  with ci-null being a package provided
only in the CI PPA to ensure the missing dep would fail in non-ci dep
resolution.

b) Have a separate branch carrying the delta gainst kubuntu_unstable
(e.g. kubuntu_unstable and kubuntu_unstable_utopic). This branch would
only ever get auto-merge changes from the main unstable branch and
itself is not ever branched or used (except for maybe future backport
workflows).

IMHO b) would probably be smartest. The problem in particular is that
with a) cmake would still act up and there'd be no way to shut it up
other than turn off cmake checks for all of utopic CI (which TBH
actually would be pretty acceptable) while with b) we can establish
overrides specific to utopic. Similarly if the install files need to
diverge because of this we have a problem.

Thoughts?

HS