[MacPorts] #56369: github portgroup: don't override an already-specified version

[MacPorts]

#56369: github portgroup: don't override an already-specified version
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  Reporter:  ryandesign  |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:
Resolution:              |   Keywords:
      Port:              |
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Comment (by ryandesign):

 One reason why `.setup` procedures are bad is that things become
 thoroughly confusing if a port needs to include two or more portgroups
 each of which has a setup procedure. See for example browser:macports-
 ports/multimedia/xmltv/Portfile. Setup procedures typically like to set
 the port name and version for you based on the parameters you specify. If
 you need to include more than one setup procedure, which one sets those
 variables for you? Which one do you call first? Does it matter?
 [https://lists.macports.org/pipermail/macports-dev/2020-May/041920.html
 Sometimes it does].

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Ticket URL: <https://trac.macports.org/ticket/56369#comment:4>
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