[MacPorts] #63710: "Unable to open port: can't read "universal_possible": no such variable" after upgrading to 2.7.1

[MacPorts]

#63710: "Unable to open port: can't read "universal_possible": no such variable"
after upgrading to 2.7.1
-----------------------+--------------------
  Reporter:  singalen  |      Owner:  (none)
      Type:  defect    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:  2.7.1
Resolution:            |   Keywords:
      Port:            |
-----------------------+--------------------

Comment (by jmroot):

 Run `sudo port -d selfupdate` for full debug output.

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Ticket URL: <https://trac.macports.org/ticket/63710#comment:3>
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