[Merge] ~tobijk/livecd-rootfs/+git/livecd-rootfs:feature/parallelization-snap-version-fixing into livecd-rootfs:ubuntu/master

[Tobias Koch]

The proposal to merge ~tobijk/livecd-rootfs/+git/livecd-rootfs:feature/parallelization-snap-version-fixing into livecd-rootfs:ubuntu/master has been updated.

Commit message changed to:

**********************************************************************
Please hold back on merging this until we have support for passing the cohort key through launchpad buildd.
**********************************************************************

Replace "snap download" with tool that uses snap store's coherence feature

This is important for parallel image builds to ensure all pre-seeded snaps have the same versions across image variants.

For more details, see:
https://code.launchpad.net/~tobijk/livecd-rootfs/+git/livecd-rootfs/+merge/360986
-- 
Your team Ubuntu Core Development Team is subscribed to branch livecd-rootfs:ubuntu/master.