[MacPorts] #54605: Update guide to tell user where to get "original" Portfile for patching

[MacPorts]

#54605: Update guide to tell user where to get "original" Portfile for patching
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  Reporter:  jfcaron3  |      Owner:
      Type:  defect    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  guide     |    Version:
Resolution:            |   Keywords:
      Port:            |
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Old description:

> If you read:
> https://guide.macports.org/#development.patches.portfile
>
> It tells you how to make a copy and generate patch for a Portfile, but it
> does not tell you where to find the original Portfile.  Looking on my
> system with find /opt/local grep|portname|grep Portfile, I find two
> candidates, one somewhere in
> /opt/local//var/macports/sources/rsync.macports.org/release/tarballs/ports
> and another somewhere in /opt/local//var/macports/registry/portfiles/ and
> they appear slightly different.
>
> Even if this is an idiosyncrasy in my system, the guide section should
> include the default location of the Portfile to be used to generate
> patches.

New description:

 If you read:
 https://guide.macports.org/#development.patches.portfile

 It tells you how to make a copy and generate patch for a Portfile, but it
 does not tell you where to find the original Portfile.  Looking on my
 system with find /opt/local grep|portname|grep Portfile, I find two
 candidates, one somewhere in
 /opt/local/var/macports/sources/rsync.macports.org/release/tarballs/ports
 and another somewhere in /opt/local/var/macports/registry/portfiles/ and
 they appear slightly different.

 Even if this is an idiosyncrasy in my system, the guide section should
 include the default location of the Portfile to be used to generate
 patches.

--

Comment (by ryandesign):

 The command `port file foo` will tell you where the Portfile for port
 ''foo'' is located.

 The registry contains a copy of the Portfile as it appeared when you
 installed the port. This may not be the current version of the Portfile,
 and if you're going to submit a patch, it should be based on the current
 version, which is in the sources directory, or, as Ken said, in our GitHub
 repository.

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Ticket URL: <https://trac.macports.org/ticket/54605#comment:2>
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