More trigger cycles

[Niels Thykier <niels@thykier.net>]

Hi,

Based on #778695, it seems like we still have trigger cycles.  At this
point in the freeze, I am afraid it is too late to fix the remaining cycles.

I have asked Johannes if this kind of trigger cycles can be found via
his script.  If so, hopefully we can have them eliminated for Stretch,
but as said - we are over 3 months into the freeze and these trigger
cycles are still biting us.

@dpkg maintainers: Please make the necessary changes to revert the
trigger cycle error or have dpkg recover from it automatically
immediately without aborting the upgrade.

Thanks,
~Niels