Improve the dispatch algorithm by avoiding unnecessary ambiguities

[wesselb]

@PhilipVinc, I've taken some time to go over #119. I've attempted to implement a very similar approach in a way that makes it very clear where precisely we deviate from the subset relationship and why that is justified.

Would you be able to check if this works for your use case? If it does, I'll add some more extensive tests based on the examples from the other PR.

[coveralls]

Pull Request Test Coverage Report for Build 9339827200

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 21 of 21 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 9223100708:	0.0%
Covered Lines:	1227
Relevant Lines:	1227

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💛 - Coveralls

[PhilipVinc]

Apart from those extra tests, this PR fixes the issues I had with plum and would allow us to stop vendoring it, so I'm supporting it in full.

Moreover, I think this is equivalent to my past PR (albeit much more elegant) so again, I think that's the right approach.

Thanks!

[wesselb]

@PhilipVinc Perfect! :) I'll then finalise this PR by adding the missing tests and merge it.

[PhilipVinc]

@wesselb can I merge? seems all is good

[wesselb]

@PhilipVinc I'm making some final tweaks. If it's ok, I'll merge this in the next ~hour.

[wesselb]

@PhilipVinc Actually, that was faster than expected. I think it looks good. I've added a comment what precisely need to be fixed to fully resolve #117. I think it's feasible to fix, but beyond the scope of this PR. Happy to merge this now?

[PhilipVinc]

happy to!

[wesselb]

Hurray! I'm pretty happy this is finally partially fixed. :)