[MacPorts] #35897: Add a buildbot with +universal for all packages

[MacPorts]

#35897: Add a buildbot with +universal for all packages
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  Reporter:  mojca          |      Owner:  macports-tickets@…
      Type:  enhancement    |     Status:  new
  Priority:  Low            |  Milestone:
 Component:  buildbot/mpbb  |    Version:
Resolution:                 |   Keywords:
      Port:                 |
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Comment (by ryandesign):

 I don't think we should build and distribute binaries of all ports with
 the universal variant. It's not needed generally and would take a lot of
 disk space, and we've already lost one of our mirrors because they ran out
 of disk space. We also do not have unlimited disk space on the buildbot
 workers, and they keep (the current version of) all ports they've built
 installed.

 We already build and distribute universal binaries when they are a
 dependency. So, when wine is updated, it builds universal variants of all
 its dependencies, such as freetype. All we need to do to complete that is
 whenever a port is updated, get the list of different variant combinations
 with which that port is currently installed on the buildbot worker, and
 schedule a build for each of those variant combinations. (So, if freetype
 is currently installed with the universal variant and with no variants,
 schedule two builds of freetype, one with the universal variant and one
 with no variants.)

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Ticket URL: <https://trac.macports.org/ticket/35897#comment:20>
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