I am trying to build the freeorion snap in a new way.
I had it building locally on a machine. After a while I switched to remote build because that gave me less troubles. I think local build somewhen did not work anymore (after the virtualisation scheme i used was dropped by snapcraft). Now I want to build using the build functionality on the snapcraft.io page. So I started recreating a snapcraft.yaml which works there.
snapcraft will default to using a xenial base (to target the core base snap). It will only use a different distro if you specify either of base or build_base (the latter being less common and is meant for building a base snap). To get your build to run on bionic to target core18 you need to add the following to your yaml:
Looking at the information about the two builds (build 1318598 and build 1318603 on Launchpad), it does look like a bug. For the two revisions built, you’ve got base: core18, but it has chosen a different container image for each build.
This probably is a problem on the build.snapcraft.io side rather than Launchpad, since I believe that’s the part that instructs Launchpad how to run the build.