[MacPorts] #64297: Allow "." as synonym for current port directory

[MacPorts]

#64297: Allow "." as synonym for current port directory
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  Reporter:  ryandesign   |      Owner:  (none)
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  base         |    Version:  2.7.99
Resolution:               |   Keywords:
      Port:               |
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Comment (by jmroot):

 This gets a bit complicated because we don't currently allow using a bare
 path to specify a port to operate on, only a port name, pseudo-portname,
 or full porturl. If we accept `.`, users might quite reasonably assume
 that any directory would be accepted in the same place. The `-D` option is
 what currently allows you to specify a path to cd to before proceeding,
 which changes the evaluation of the `current` pseudo-portname among other
 things.

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Ticket URL: <https://trac.macports.org/ticket/64297#comment:1>
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