[MacPorts] #15520: upgrade processes the same dep multiple times if different depspecs are used

[MacPorts]

#15520: upgrade processes the same dep multiple times if different depspecs are
used
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 Reporter:  jmr at macports.org  |       Owner:  macports-tickets at lists.macosforge.org
     Type:  defect            |      Status:  new                                  
 Priority:  Low               |   Milestone:  MacPorts base bugs                   
Component:  ports             |     Version:  1.7.0                                
 Keywords:                    |  
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 The depscache is meant to prevent the same port from being upgraded more
 than once. However, it stores full depspecs, so if one port depends on
 bin:perl:perl5.8 and another on port:perl5.8, perl5.8 will be upgraded
 twice. This is usually a non-issue, but it causes extra port rebuilds if
 -f is used.

 I suggest a two-part fix:
  1. Always skip processing foo if port:foo is in the depscache, and
  2. When processing a dep with a depspec other than port:, add a port:
 entry to the depscache if and only if the port actually ends up being
 installed.

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Ticket URL: <http://trac.macports.org/ticket/15520>
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