Regression with ellipsis handling in v1.9.0

[aiudirog]

Bug Report

With v1.9.0, ... no longer appears to be considered the only instance of the EllipsisType and this causes type narrowing to not function properly.

To Reproduce

from types import EllipsisType
x: int | str | EllipsisType = ...
y: int | str = 0 if x is ... else x

https://mypy-play.net/?mypy=1.9.0&python=3.12&flags=strict&gist=02e73fd9b069629261e7328ab3530973

Expected Behavior

No errors, as it behaved on 1.8.0:

Success: no issues found in 1 source file

Actual Behavior

main.py:3: error: Incompatible types in assignment (expression has type "int | str | EllipsisType", variable has type "int | str")  [assignment]
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 1.9.0
• Mypy command-line flags: --strict
• Mypy configuration options from mypy.ini (and other config files): N/A
• Python version used: 3.10.13 & 3.12 (in the playground)

[JelleZijlstra]

Duplicate of #17002

[aiudirog]

My apologies, I must have only checked open tickets and didn't see the closed one