Guard against completions in wrong runs
Guard against completions in wrong runs

We get sometimes stake symbol error because a completer
is run in its creation context, which comes from a previous run.
This should not happen. Adding an assert to flag the erronenous
completion when it happens.

som-snytt/dotty,dotty-staging/dotty,dotty-staging/dotty,dotty-staging/dotty,sjrd/dotty,dotty-staging/dotty,som-snytt/dotty,som-snytt/dotty,lampepfl/dotty,sjrd/dotty,som-snytt/dotty,sjrd/dotty,lampepfl/dotty,lampepfl/dotty,sjrd/dotty,dotty-staging/dotty,som-snytt/dotty,sjrd/dotty,lampepfl/dotty,lampepfl/dotty