Bug#779876: gcc-4.9-base: please add Breaks: gnat-4.6-base (<< 4.6.4)

[Andreas Beckmann <anbe@debian.org>]

Package: gcc-4.9-base
Version: 4.9.1-19
Severity: important
User: debian-qa@lists.debian.org
Usertags: piuparts


Hi,

during my piuparts wheezy->jessie upgrade tests I noticed some cases
where gnat-4.6 was kept installed and gnat-4.9 was not being installed,
holding back some more old packages on the way.
This should be fixable by adding
  Breaks: gnat-4.6-base (<< 4.6.4)
to gcc-4.9-base (the Breaks on gnat-4.6 (<< 4.6.1-5~) could be removed
at the same time).
Unfortunately I didn't have the time right now to test this locally.

apt problemresolver debug output from such a failure:

  Starting 2
  Investigating (0) gnat-4.9 [ amd64 ] < none -> 4.9.1-4 > ( devel )
  Broken gnat-4.9:amd64 Conflicts on gnat-4.6 [ amd64 ] < 4.6.3-8 > ( devel )
    Considering gnat-4.6:amd64 0 as a solution to gnat-4.9:amd64 0
    Holding Back gnat-4.9:amd64 rather than change gnat-4.6:amd64
  Investigating (0) libpolyorb3-dev [ amd64 ] < none -> 2.11~20140418-3 > ( libdevel )
  Broken libpolyorb3-dev:amd64 Depends on gnat-4.9 [ amd64 ] < none -> 4.9.1-4 > ( devel )
    Considering gnat-4.9:amd64 0 as a solution to libpolyorb3-dev:amd64 0
    Holding Back libpolyorb3-dev:amd64 rather than change gnat-4.9:amd64
  Investigating (0) libpolyorb-dbg [ amd64 ] < 2.8~20110207-5.1 -> 2.11~20140418-3 > ( debug )
  Broken libpolyorb-dbg:amd64 Depends on libpolyorb3-dev [ amd64 ] < none -> 2.11~20140418-3 > ( libdevel ) (= 2.11~20140418-3)
    Considering libpolyorb3-dev:amd64 0 as a solution to libpolyorb-dbg:amd64 -1
    Holding Back libpolyorb-dbg:amd64 rather than change libpolyorb3-dev:amd64
   Try to Re-Instate (1) libpolyorb-dbg:amd64
  Done

Unfortunately the scoring resulted a tie for gnat-4.6 and gnat-4.9 
which was resolved in favor of the installed package.

With the suggested Breaks the whole gnat-4.6 stack from wheezy will be
removed on upgrades to jessie (whcih has no gnat-4.6) (alternatively
the gnat-4.6 stack from sid could be installed).

This fix needs to get into jessie, I'll do intensive upgrade tests once
it is there.


Andreas