Configure hook breaks content interface plug

[Pat McGowan]

Start with a working snap which plugs the ubuntu-app-platform interface.
Add a configure hook (meta/hooks/configure) to the snap
The snap will no longer start, and always reports
You need to connect this snap to the ubuntu app platform snap.

Snap interfaces shows the connection.
$ snap --version
snap 2.22.7
snapd 2.22.7
series 16
ubuntu 16.04
kernel 4.4.0-64-generic

Tested on my laptop, have not yet tried on core.

[Pat McGowan (pat-mcgowan)]

Running sudo /usr/lib/snapd/snap-discard-ns <snap> fixes it. Sounds related to lp:1645731

[Kyle Fazzari (kyrofa)]

Confirmed. This is particularly weird considering a few things:

1) The content interface to the ubuntu-app-platform is automatically connected, even if the consumer is --dangerous. I assume this is a slot-side assertion.
2) The configure hook specifically runs _after_ services in the snap, which means confinement (including the content interface since it's automatically connected) should be put together by then.