[MacPorts] #56411: opencv @3.4.1_2 +python27 fails to build on 10.13.4 HighSierra

[MacPorts]

#56411: opencv @3.4.1_2 +python27 fails to build on 10.13.4 HighSierra
------------------------+----------------------
  Reporter:  duchowski  |      Owner:  stromnov
      Type:  defect     |     Status:  assigned
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:  2.4.3
Resolution:             |   Keywords:
      Port:  opencv     |
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Comment (by pmetzger):

 I suspect this is the issue:

 {{{
 depends_lib-append      path:${prefix}/lib/libprotobuf.dylib:protobuf-cpp
 }}}

 We're in the middle of a protobuf-cpp to protobuf3-cpp transition and this
 variant seems to have somehow been missed in our list of things to look
 at. The way that is written, it will depend on whatever version of
 protobuf happens to be installed, which probably means that you can get
 bad accidents.

-- 
Ticket URL: <https://trac.macports.org/ticket/56411#comment:4>
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