git-ubuntu.experimental-build invokes system commands with snap-specific environment

[Michael Hudson-Doyle]

If you run git-ubuntu.experimental-build on mantic you get this:

(ubuntu/devel)mwhudson@orcrist:~/src/pkg/icedtea-web$ git-ubuntu.experimental-build -- -S
Cwd.c: loadable library and perl binaries are mismatched (got first handshake key 0xcd00080, needed 0xeb80080)

I think the issue here is that git-ubuntu's meta/snap.yaml sets PERL5LIB to point inside the snap and when experimental-build runs dpkg-buildpackage from the host (which is a perl script), /usr/bin/perl tries to load compiled extensions from the snap (i.e. focal) and complains.

I think git-ubuntu needs to grow some kind of helper to run system binaries with a clean or at least clean-enough environment (PYTHONPATH could definitely cause similar issues).

(Classic snaps are a hoot)

[Michael Hudson-Doyle (mwhudson)]

Ah yes PYTHONPATH causes similar issues when invoking gbp