[MacPorts] #57457: Travis CI: Sometimes declared dependencies aren't installed

[MacPorts]

#57457: Travis CI: Sometimes declared dependencies aren't installed
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 Reporter:  ryandesign      |      Owner:  admin@…
     Type:  defect          |     Status:  new
 Priority:  Normal          |  Milestone:
Component:  server/hosting  |    Version:
 Keywords:                  |       Port:
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 At Zero King's request, I'm breaking this issue out from #56300.

 Travis sometimes experiences errors that should be impossible, such a
 dependency which is definitely declared not being installed, which then
 results in a failure.

 Here is an example of this:

 * The PR: https://github.com/macports/macports-ports/pull/2874
 * One of the resulting Travis CI builds: https://travis-ci.org/macports
 /macports-ports/jobs/446238426
 * The log of the failure of that build:
 https://paste.macports.org/9e2079261585
 * The relevant error from that log:

 {{{
 --->  Extracting coreutils
 Error: Failed to extract coreutils: Failed to locate 'xz' in path:
 '/opt/local/bin:/opt/local/sbin:/bin:/sbin:/usr/bin:/usr/sbin' or at its
 MacPorts configuration time location, did you move it?
 DEBUG: Error code: NONE
 }}}

 The coreutils port definitely has an extract dependency on xz, added by
 MacPorts because of its .xz distfile, and 2 of the other builds started
 from this PR built fine. (The 4th failed due to an unrelated issue.)

 This issue is specific to whatever we're doing on Travis CI; I've never
 seen this problem with the buildbot.

-- 
Ticket URL: <https://trac.macports.org/ticket/57457>
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