[MacPorts] #69661: Disable Homebrew on Apple Silicon GitHub Actions CI runners

[MacPorts]

#69661: Disable Homebrew on Apple Silicon GitHub Actions CI runners
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  Reporter:  ryandesign      |      Owner:  admin@…
      Type:  defect          |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  server/hosting  |    Version:
Resolution:                  |   Keywords:
      Port:                  |
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Comment (by ryandesign):

 I'm not sure why the macports-base and macports-ports workflows use two
 different strategies for disabling Homebrew. Seems like there should be a
 single script to do that that can be called from both places.

 Or, why does the macports-base workflow need to disable Homebrew at all?
 We already know that we should set `PATH=/usr/bin:/bin:/usr/sbin:/sbin`
 before running `./configure` to avoid pulling in dependencies from an
 already-installed MacPorts. If we had done that, we would have avoided
 pulling in dependencies from Homebrew and anywhere else too.

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Ticket URL: <https://trac.macports.org/ticket/69661#comment:4>
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