Sqlalchemy backend with AppendQuery fails

TypeError: Mixer (): 'object' object is not iterable.

Investigations suggest this has to do with sqlalchemy_continuum and the 'versions' attribute.

This should be a new ticket, but applying SKIP to the versions attribute does nothing or that is to say, that the failure is something else entirely. It still appears to attempt to set the SKIP attribute, which is counterintuitive at best and a possible bug.

No file or test is named in the issue. Start at the SQLAlchemy backend and reproduce the TypeError with app.models.Phone and sqlalchemy_continuum's versions attribute; then inspect how SKIP is handled there. Done means the reported case no longer fails and the intended SKIP behavior is verified by a regression test.

Written by the indexing model from the issue text.