allOf fails if it references a type that also uses allOf with just single item

[eli-bl]

Describe the bug

Conditions:

• Schema A is a type with any definition.
• Schema B contains only an allOf with a single element referencing Schema A.
• Schema C contains an allOf that 1. references Schema B and 2. adds a property.

Expected behavior:

• Spec is valid. Schema B should be treated as exactly equivalent to Schema A (in other words, C becomes an extension of A with an extra property).

Observed behavior:

• Parsing fails. Error message is "Unable to process schema ".

OpenAPI Spec File
https://gist.github.com/eli-bl/8f5c7d1d872d9fda5379fa6370dab6a8

Desktop (please complete the following information):

• OS: macOS 14.5
• Python Version: 3.8.15
• openapi-python-client version 0.21.2