Depends on D20106. Ref T6703. Since I plan to change the ExternalAccount table, these migrations (which rely on save()) will stop working.
They could be rewritten to use raw queries, but I suspect few or no installs are affected. At least for now, just make them safe: if they would affect data, fatal and tell the user to perform a more gradual upgrade.
Also remove an ALTER IGNORE TABLE (this syntax was removed at some point) and fix a %Q when adjusting certain types of primary keys.