AutoMerge: switch to RegistryInstances

[ericphanson]

this ends up kind of undoing #614 because it seemed easier to use RegistryInstances everywhere. Now we can use packed registries everywhere except the RegistryCI.jl-based check which needs to support older Julia's. In particular, this should make it more feasible to set up a "local" version that users can use without needing a unpacked registry.

written by claude-code but with a very annoying amount of iteration, probably it would have been faster to do it myself.

The most gnarly checks here are the deps and julia compat, and I tested that we got the same results on the latest release of all 11k packages (this did reveal a bug in the initial implementation, in which there was only a julia dep and no other deps). I also included some tests with the old version on a few packages to show they are the same, but we could delete those tests before merging if we want.

[codecov[bot]]

Codecov Report

:x: Patch coverage is 66.94915% with 39 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 51.20%. Comparing base (9818af3) to head (3b03c9b).

Files with missing lines	Patch %	Lines
AutoMerge/src/guidelines.jl	69.76%	13 Missing :warning:
AutoMerge/src/dependency_confusion.jl	0.00%	8 Missing :warning:
AutoMerge/src/package_path_in_registry.jl	0.00%	6 Missing :warning:
AutoMerge/src/registry_helpers.jl	84.84%	5 Missing :warning:
AutoMerge/src/jll.jl	0.00%	4 Missing :warning:
AutoMerge/src/semver.jl	78.57%	3 Missing :warning:

:x: Your project check has failed because the head coverage (51.20%) is below the target coverage (70.00%). You can increase the head coverage or adjust the target coverage.

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HEAD has 13 uploads less than BASE

Flag	BASE (9818af3)	HEAD (3b03c9b)
	24	11

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #643       +/-   ##
===========================================
- Coverage   78.40%   51.20%   -27.21%     
===========================================
  Files          29       29               
  Lines        1936     1914       -22     
===========================================
- Hits         1518      980      -538     
- Misses        418      934      +516     

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[DilumAluthge]

So, if I understand correctly, you're only using RegistryInstances (and the packed registry) for the upstream registry head, right? For the checked-out PR branch, you're still using the unpacked registry that we have checked out on disk?

Do I have that correct?

[ericphanson]

no, I'm using RegistryInstances for both. It can handle both packed and unpacked registries

[ericphanson]

@GunnarFarneback I know you might not have time for a full review, but do you have any thoughts on this approach?

[GunnarFarneback]

I think it's generally fine and simplifies some of the registry analysis code.