--shell does not make snapcraftctl available

[Robie Basak]

$ snapcraft pull --use-lxd --shell acme

To debug my override-pull.

Expected: "snapcraftctl pull" works.

Actual:

# snapcraftctl pull
bash: snapcraftctl: command not found

[Casper (casper-dcl)]

also doesn't work with `--shell-after`

[Andreas Hasenack (ahasenack)]

I'm debugging a case where snapcraftctl build clearly fails, but its exit status is 0. It would be super helpful if I could run it by hand in the so called interactive shell that snapcraft dumps me into when using --debug, but as it is, I don't know where to call it from, not even if it will run once I find it (env vars?).