Fix caching of remote source tarballs

[hasufell]

Fixes #11511

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[hasufell]

I don't fully understand what was going on here, but it appears that running monitorFiles within rerunIfChanged seems to be problematic and breaks the "mtime of downloaded tarball" >= "monitor start time" condition, constantly re-triggering a download. I simply floated it out and the problem is gone.

I verified that it still re-downloads when I change the URL, which seems to be the primary use case.

I'm not sure how I would create a test for this.

[ffaf1]

Template B: This PR does not modify behaviour or interface

Apparently this does modify behaviour, does it not?

[hasufell]

Template B: This PR does not modify behaviour or interface

Apparently this does modify behaviour, does it not?

Well, I guess. But not in a way that breaks user interfaces.

[hasufell]

Here's proof that the test captures the failure: https://github.com/haskell/cabal/actions/runs/22380895412?pr=11512

[hasufell]

@ffaf1 is there anything else?

[ffaf1]

Nope, you can put the label!

[mergify]

Merge Queue Status

Rule: default

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• ✅ Entered queue — 2026-03-04 10:03 UTC
• ✅ Checks passed · on draft merge queue: embarking master (67690f2) and #11512 together #11572
• ✅ Merged — 2026-03-04 12:09 UTC · at 02559953982f7f15c185eb8720a6d35bcee22e16

This pull request spent 2 hours 5 minutes 15 seconds in the queue, including 1 hour 54 minutes 49 seconds running CI.

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