Emit an error message if the user tries to change the collection ID of
an existing repository between two non-empty values. Allow them to set a
collection ID where one was not set before. Changing the collection ID
once it’s already been set will break updates for all clients who have
previously pulled from the repository.
If a developer really wants to change the collection ID for a
repository, they’re going to have to recreate the repository from
scratch.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
b6828cda31