fix: subject_type for "foo:bar" event tags

[divbzero]

The EventTagEnum docstring indicates that omitted subject_type should fallback to source_type:

warehouse/warehouse/events/tags.py

Line 26 in 53babdb

If omitted, subject type is implied to be the same as source type.

However, a typo resulted in EventTagEnum("foo:bar") to have "f" instead of "foo" for subject_type.

[miketheman]

How does this manifest? Feels odd to see a fix like this with no failing or updated tests?

[divbzero]

@miketheman I don’t think it actually manifests. subject_type is defined for EventTagEnum but isn’t used anywhere in the code base.

I contributed to pypi/warehouse awhile back and was reading the code again as a reference for a different project I’m working on. Just happened to spot this typo.

Does the fix look sensible as is? Would we want to add tests, or perhaps remove source_type, subject_type, and action from __new__ if they aren’t used anywhere?

[miketheman]

Does the fix look sensible as is? Would we want to add tests, or perhaps remove source_type, subject_type, and action from __new__ if they aren’t used anywhere?

I'm thinking that if we don't actually make the distinction anywhere, and use it as the raw string, the parsing/assignment could be removed? But on the off chance we do use it in some weird way, it's probably safer to keep it, so adding tests is a better approach - maybe the tests would show the intended usage.