[MacPorts] #62340: cask +python27 also depends on python39

[MacPorts]

#62340: cask +python27 also depends on python39
------------------------+----------------------
 Reporter:  ryandesign  |      Owner:  amake
     Type:  defect      |     Status:  assigned
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:  2.6.4
 Keywords:              |       Port:  cask
------------------------+----------------------
 cask without a variant selected depends on python39; fine:
 {{{
 $ port info cask
 cask @0.8.5_1 (devel)
 Variants:             python27

 Description:          Cask is a project management tool for Emacs that
 helps automate the package development cycle; development, dependencies,
 testing, building, packaging and more. Cask can also be used to manage
 dependencies for your
                       local Emacs configuration.
 Homepage:             https://github.com/cask/cask

 Library Dependencies: python39
 Platforms:            darwin
 License:              GPL-3+
 Maintainers:          Email: amake at macports.org, GitHub: amake
                       Policy: openmaintainer
 }}}

 But cask +python27 depends on both python39 and python27; not expected:
 {{{
 $ port info cask +python27
 cask @0.8.5_1 (devel)
 Variants:             +python27

 Description:          Cask is a project management tool for Emacs that
 helps automate the package development cycle; development, dependencies,
 testing, building, packaging and more. Cask can also be used to manage
 dependencies for your
                       local Emacs configuration.
 Homepage:             https://github.com/cask/cask

 Library Dependencies: python39, python27
 Platforms:            darwin
 License:              GPL-3+
 Maintainers:          Email: amake at macports.org, GitHub: amake
                       Policy: openmaintainer
 }}}

 Why does the port need a python27 variant at all?

 If it does need a python27 variant, then it should also have a python39
 variant, and the two should be marked conflicting, and the port should
 ensure that one or the other is selected. This makes it clearer to the
 user that they are making a choice between two options (radio buttons),
 rather than a choice between whether or not to have an optional feature
 (checkbox).

-- 
Ticket URL: <https://trac.macports.org/ticket/62340>
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