Builds don't use "build-snaps" by default because of $PATH precedence

[Christopher Townsend]

On Multipass, we've recently switched to using "build-snaps: [cmake]" in order to use a newer version of cmake in 18.04 based builds. This works fine when using snapcraft, but fails on launchpad-buildd.

Here is an example failure: https://snapcraft.io/multipass/builds/1046296

After a bit of research, I found this forum post: https://forum.snapcraft.io/t/build-service-fails-to-use-cmake-from-build-snap/17973

In short, $PATH has /snap/bin at the end, so launchpad-buildd will prefer the deb version of cmake.

Sure, we can force $PATH in our snapcraft.yaml, but I feel this behavior is inconsistent between snapcraft itself and launchpad-buildd.

Thanks!

[Christopher Townsend (townsend)]

I'm only entering this bug based on the recommendation in https://forum.snapcraft.io/t/build-service-fails-to-use-cmake-from-build-snap/17973/13, but I do think Snapcraft is ultimately the right place for this to be addressed.

Please close if you feel there is nothing that should be done here.