`if TYPE_CHECKING` blocks not considered when resolving symbols

[cjw296]

I'm trying to use sphinx-autodoc-typehints to work around sphinx-doc/sphinx#10785.

However, I need to use an if TYPE_CHECKING block to resolve an unavoidable circular import issue:

https://github.com/simplistix/sybil/blob/f6d8772a3f0b32c79a0b4cdd83d21098cb0721a7/sybil/typing.py#L1-L14

However, now I get:

WARNING: Cannot resolve forward reference in type annotations of "sybil.Sybil": name 'sybil' is not defined

...because it doesn't appear this package is considering imports within the if TYPE_CHECKING.

[hoodmane]

I think this is a duplicate of #22?

[cjw296]

Yep