[MacPorts] #54800: Cache built dependency packages on Travis CI to speed up testing flow

[MacPorts]

#54800: Cache built dependency packages on Travis CI to speed up testing flow
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  Reporter:  yan12125        |      Owner:  admin@…
      Type:  enhancement     |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  server/hosting  |    Version:
Resolution:                  |   Keywords:
      Port:                  |
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Changes (by mojca):

 * cc: l2dy (added)


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Ticket URL: <https://trac.macports.org/ticket/54800#comment:2>
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