Comment 6 for bug 1510813

Harry,
  xenial-proposed (devel-proposed) is by definition pretty broken, see [1]. Sure you are free to use it, and maybe in some limited cases it will work, but overall its pretty much guaranteed that packages in there have broken dependencies or failing tests. This is vastly different from the stable <release>-proposed pockets

eog and mutter and all the reverse-depends will be rebuilt against 3-12, once we start the transition (waiting for evolution-data-server transition to clear first), and then everything will migrate to the release pocket...

So basically unless I am missing something, there is nothing to fix here?

[1]https://wiki.ubuntu.com/ProposedMigration