Fix related item import fallback keys

[djbe]

Implements #1170, without the extra code.

[Coeur]

Related: #1169

[Coeur]

You wrote:

On that note, the MR_lookupKeyForAttribute: method might need some changing. At least the parameter type should be changed from NSAttributeDescription to NSPropertyDescription, to correctly match both use cases.

But you did not apply this change in your Pull Request.

Well, thank you for the Pull Request, and sorry for looking at it so late, but a unit test demonstrating the resolved issue is needed before I merge any fix.

[djbe]

Wow, talk about a blast from the past 😆

I haven't used this library in a few years, so I don't have any files ready to use as a unit test. I don't even remember in which of my projects I encountered this issue 😅

But I can guess from the original issue's description what the issue was (fallback import paths for relationships). If I find some time for this, I'll take a stab at some unit tests.

[Coeur]

Wow, talk about a blast from the past 😆

Ik weet.
The repository has been abandoned, but I recently found the time to review every pending pull request (for the 2.x version of MagicalRecord). It's too much work to create unit tests myself for every case, so I'll be conservative and I won't merge until then.