[MacPorts] #60581: garbage error output from failed curl

[MacPorts]

#60581: garbage error output from failed curl
-------------------------+----------------------------
  Reporter:  ryandesign  |      Owner:  neverpanic
      Type:  defect      |     Status:  closed
  Priority:  Normal      |  Milestone:  MacPorts 2.6.3
 Component:  base        |    Version:  2.6.2
Resolution:  fixed       |   Keywords:
      Port:              |
-------------------------+----------------------------

Comment (by neverpanic):

 Just seen this in build output generated by Travis, and the change seems
 to work as expected. See https://paste.macports.org/75dc136dfd83:

 {{{
 Error: Failed to fetch py38-lxml: curl_multi_info_read() returned {.msg =
 CURLMSG_DONE, .data.result = 7 (!= CURLE_OK)}, but the error buffer is not
 set. curl_easy_strerror(.data.result): Couldn't connect to server
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/60581#comment:6>
MacPorts <https://www.macports.org/>
Ports system for macOS