Bug Report: RenameField and RenameModel operations don't work

[ThomasAitken]

First of all, thank you again for this library, and thank you for your recent changes to support MySQL. A follow up on my earlier issue is that I ended up creating a version of this where I alter Django's default dependency graph so that pre-deploy migrations can always be run on their own, even if out of sequence. I am not planning to submit a pull request for this, although please let me know if you are interested in this concept and I can explain more (it relies on the concept that a pre-deploy migration need never actually rely on a post-deploy migration).

Anyhow, this issue is a bug report

First bug

This is a bug that causes migrations containing RenameField and (I suspect) RenameModel operations to fail completely.

Steps to reproduce:

1. Rename a field
2. Run makemigrations
3. Confirm field renaming in questioning flow
4. Select one of the two latter options

Now try to plan/run the newly generated migration using python manage.py migrate. You get an error trace like this:

  File "/Users/admin/ClipsalRepos/helios/clippy/migrations/0156_rename_nem3_state_tariffrate_nem4_state.py", line 7, in <module>
    class Migration(migrations.Migration):
  File "/Users/admin/ClipsalRepos/helios/clippy/migrations/0156_rename_nem3_state_tariffrate_nem4_state.py", line 14, in Migration
    syzygy.operations.RenameField(),
  File "/Users/admin/Library/Caches/pypoetry/virtualenvs/helios-EL_XmWmL-py3.10/lib/python3.10/site-packages/syzygy/operations.py", line 309, in __init__
    self.stage = kwargs.pop("stage")
KeyError: 'stage'

Commentary

Line 120 in autodetector.py is meant to prevent this: operation = RenameField.for_stage(operation, stage) by re-initialising the operation class with the appropriate stage

But the generated migration uses a new instance of this class, so this line does nothing.

Second Bug

The questioner flow uses 0-based indexing for the choices but it should be 1-based indexing because they're displayed as 1, 2, 3, 4.

Apologies if I somehow misunderstood something with regard to either of these two bugs