0001_initial to 0024_log_retention_setting are mostly RunPython steps
that added, renamed, re-chose and described setting rows since 2020. A
squashed migration now creates the table in its final shape and inserts
the 38 rows those steps leave; it replaces all 24, so a new database
runs it alone. The 24 stay beside it, as Django's squashing expects
until every installation has applied them: a database that applied
them all records the squashed one without running anything, and one
that stopped between them (an older release, or an upstream
installation) applies the rest of them first.
Checked:
- on a new database its rows equal the old chain's (name, key, value,
choices, description of every row);
- on a copy of a running panel's database (all 24 applied) migrate
plans nothing for appsettings;
- a database migrated by the old code to 0023 applies 0024 and then
records the squashed migration, with the same 38 rows;
- makemigrations finds no change.
It inserts its rows on the database being migrated, as the replaced steps
do. The tests of the replaced steps stay, since an installation that stopped
between them still runs them; the two that checked a few rows' columns
became one that checks every row's columns and description, and a value is
one of its choices.
