+1 maint - phpunit 9 bootstrap proposal

[Bryce Harrington]

phpunit has been stuck in a 8.5 -> 9.5 transition, which blocks other
things.  I'd like to propose we back out 9.5 and bootstrap to 9.0, and
*then* to 9.5.


In looking at the phpunit builds on update_excuses, phpunit 9.5 fails to
build due to three of its dependencies, which themselves are failing to
build because they in turn have phpunit 9.x as build dependencies.
E.g.:

  phpunit unsatisfiable Build-Depends(-Arch) on amd64: php-codecoverage (>= 9)

  php-codecoverage 9.2.5+dfsg-2 shows "Missing build dependencies: phpunit (>= 9)"

(Near as I can tell, the packages depend on phpunit only for
running the testsuite in debian/rules' override_dh_auto_test.  The
packages don't appear to actually depend on any code from phpunit.)

Debian did not jump straight from 8.5 to 9.5, but rather went through
the intermediate versions in Experimental.  It looks like phpunit 9.0.0
might be new enough to satisfy various built requirements, without
having too intensive build requirements itself.

RAOF suggested one option might be to do similarly - remove phpunit from
-proposed, stage the intermediary pieces in a PPA, and then
source+binary copy them into the archive.  I've staged the pieces, with
their testsuites disabled, here:

  https://launchpad.net/~bryce/+archive/ubuntu/phpunit-bootstrap/+packages

Once that phpunit is happily in the archive, I believe the remainder of
the phpunit stack should be able to be rebuilt, and then phpunit 9.5
could be re-introduced and hopefully complete the phpunit transition.

Neither RAOF or I have worked on phpunit previously, and we're not
certain that this is the proper approach, so would appreciate a thumb's
up or course correction from Vorlon, Xnox, etc., before we actually do
it.  Is this a sensible path?

Bryce