Comment 3 for bug 1918705

OK so trying this:

```
name: try-kiosk-x11
version: none
summary: Segfault on stage-snaps
description: |
  This shows snapcraft segfaulting on stage-snaps
confinement: strict
base: core18

parts:
  mir-kiosk:
    plugin: nil
    stage-snaps:
      - mir-kiosk-x11
```

Fails as expected, because mir-kiosk-x11 is core20-based. But changing it to `/latest/beta` and rebuilding without cleaning will segfault again. After clean, it works correctly.