Bitbucket will kill all its Mercurial repositories on 01-Jun-2020, see also:
* Official announcement: https://bitbucket.org/blog/sunsetting-mercurial-support-in-bitbucket
* Summary of the affair and offer by a different provider: https://community.atlassian.com/t5/Bitbucket-articles/What-to-do-with-your-Mercurial-repos-when-Bitbucket-sunsets/ba-p/1155380
It is the responsibility of the AFP editors to come up with a plan that fits to the underlying technology: Isabelle with its existing tooling for Mercurial (e.g. for long-term test data, paring of Isabelle vs. AFP changeset ids).