[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 singalen):

 Indeed. Looking for more diagnostics...

 {{{
 $ sudo port selfupdate
 Password:
 --->  Updating MacPorts base sources using rsync
 MacPorts base version 2.6.3 installed,
 MacPorts base version 2.7.1 downloaded.
 --->  Updating the ports tree
 $ echo $?
 0
 $ sudo port selfupdate
 --->  Updating MacPorts base sources using rsync
 MacPorts base version 2.6.3 installed,
 MacPorts base version 2.7.1 downloaded.
 --->  Updating the ports tree
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/63710#comment:2>
MacPorts <https://www.macports.org/>
Ports system for macOS