When running SQLite 2.26+ and Django 1.11 through 2.1.4, an Alter Table

would fail silently, causing problems further down the line. This was

due to some behavioral changes in SQLite when altering tables that

Django was not compatible with.
Django 2.1.4 turns on the legacy_alter_table flag when preparing to

edit schema. We now patch earlier versions of Django to do the same

thing.

Tested in a Python environment with these versions and reproduced

the problem and the fix.