[MacPorts] #23125: graphics/libpng update version, tweak livecheck

[MacPorts]

#23125: graphics/libpng update version, tweak livecheck
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 Reporter:  rmsfisher@…             |       Owner:  ryandesign@…           
     Type:  update                  |      Status:  assigned               
 Priority:  Normal                  |   Milestone:                         
Component:  ports                   |     Version:                         
 Keywords:                          |        Port:  libpng                 
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Comment(by ryandesign@…):

 You're right, there would be a lot of ports to revbump, not just those
 that list libpng as a dependency, but also those that indirectly use
 libpng, which we may only discover through analyzing our installed ports,
 or worst case through bug reports later. But we've successfully used this
 revbump strategy with jpeg 7 and again with jpeg 8.

 My concern with Joshua's proposal is the hack for deactivating libpng
 @1.2.x before installing libpng12. It can be simplified a bit now that
 MacPorts 1.9.0 is out, but it's still using commands that were not meant
 to appear in Portfiles. Though it's not like we haven't used various
 internal MacPorts methods in other ports before. (I know I'm guilty of
 this with php5.) And perhaps keeping both libpng12 @1.2.x and libpng
 @1.4.x is a good idea for now, since probably some software still doesn't
 work with libpng 1.4.x yet.

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Ticket URL: <http://trac.macports.org/ticket/23125#comment:11>
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