Comment 39 for bug 1551623

It could be that Debian won't need this change. Looks like all the triggers are now processed near the end of upgrade, due to changes in dpkg itself.

Possibly related entry from dpkg 1.19.3 changelog:

  * dpkg: Introduce a new dependency try level for trigger processing. This
    completely defers trigger processing until after the dependency cycle
    breaking level, so to avoid generating artificial trigger cycles, when we
    end up trying to process triggers with yet unsatisifiable dependencies.
    Closes: #810724, #854478, #911620

https://bugs.debian.org/810724

And from dpkg 1.19.7 changelog:

  * dpkg: Split the trigger dependtry into two, the second of which will be
    the one checking trigger cycles when deferring trigger processing due to
    unsatisfiable dependencies. Closes: #928429

https://bugs.debian.org/928429