[core22] gnome ext prevents use of configure hook

[Tony Espy]

When building a snap using the experimental core22 'gnome' extension in snapcraft 7, a command-chain is added to the configure hook which seems to prevent a snap-provided configure hook from running.

hooks:
    configure:
        plugs:
        - desktop
        command-chain:
        - snap/command-chain/hooks-configure-fonts

This command doesn't seem to chain properly, as it seems to prevent an actual configure hook from being called.

I've also provided a sample based on the Desktop team's workshops snap which can be found here:

https://github.com/tonyespy/workshops/tree/configure-hook-bug

To test, build the snap from my branch, install, and then run `snap set workshops foo=bar`. You'll see the following messages in the journal:

Started snap.workshops.hook.configure.a4520ba7-bb96-43f0-854e-7a34bdb3b648.scope.
snap.workshops.hook.configure.a4520ba7-bb96-43f0-854e-7a34bdb3b648.scope: Deactivated successfully.

...but not the message logged by the configure hook, nor will the file $SNAP_COMMON/configure-hook-run exist.

snapcraft version: 7.1.3 8187 (amd64)
build environment: 22.04 Desktop

[Tony Espy (awe)]

The extension adds:

hooks:
    configure:
        plugs:
        - desktop
        command-chain:
        - snap/command-chain/hooks-configure-fonts

...which should lead to snapd calling snap/command-chain/hooks-configure-fonts, then `snap/hooks/configure`. The the latter is never called in this case.

The bug is that the command-chain `hooks-configure-fonts` script that gets installed by the extension runs the command:

exec "${SNAP}/snap/command-chain/run" "${SNAP}/gnome-platform/command-chain/hooks-configure-fonts" "$@"

The script run actually checks for the existence of `${SNAP}/gnome-platform/command-chain/hooks-configure-fonts`, doesn't find it (because it's not available from the gnome-42-2204 snap), and silently exits using exit (v.s. exit 1 which would cause the hook to fail).

[Ken VanDine (ken-vandine)]

This should be fixed with https://github.com/snapcore/snapcraft-desktop-integration/pull/9