Bug#988591: lintian: please error if Test-Command ends with an &

[Adam Borowski <kilobyte@angband.pl>]

Package: lintian
Version: 2.104.0
Severity: wishlist

Hi!
I found that a lot of packages declare an autopkgtest where the Test-Command
backgrounds itself.  This does nothing useful, as eg:
    Test-Command: false &
passes successfully.  As the return value is ignored, any way such a test
can possibly fail is due to a stderr message that wins a race with
autopkgtest harness finishing.  But even that rarely does work:
    Test-Command: xvfb-run -a /usr/bin/gcrytsal &
hasn't failed "for real" yet.

In most cases, this seems to be copy-pasta of xvfb-run for GUI programs.

There's no way to reliably spot un-waited-for backgroundings in long-form
tests (ie, ones shipped in a separate file), but checking for Test-Command
ending in an & should catch current crop of offenders.