[MacPorts] #57719: archive_site_local URLs are attempted twice

[MacPorts]

#57719: archive_site_local URLs are attempted twice
------------------------+----------------------------
 Reporter:  ryandesign  |      Owner:  (none)
     Type:  defect      |     Status:  new
 Priority:  Normal      |  Milestone:  MacPorts 2.6.0
Component:  base        |    Version:  2.5.99
 Keywords:              |       Port:
------------------------+----------------------------
 With `archive_site_local`'s basic functionality fixed (#57717), we now see
 that the specified site is tried twice. With macports.conf containing:

 {{{
 archive_site_local https://packages-private.macports.org/:tbz2
 }}}

 We see:

 {{{
 --->  Fetching archive for libpng
 DEBUG: Executing org.macports.archivefetch (libpng)
 DEBUG: euid/egid changed to: 0/0
 DEBUG: chowned /opt/local/var/macports/incoming to macports
 DEBUG: euid/egid changed to: 502/501
 --->  libpng-1.6.36_0.darwin_15.x86_64.tbz2 doesn't seem to exist in
 /opt/local/var/macports/incoming/verified
 --->  Attempting to fetch libpng-1.6.36_0.darwin_15.x86_64.tbz2 from https
 ://packages-private.macports.org/libpng
   % Total    % Received % Xferd  Average Speed   Time    Time     Time
 Current
                                  Dload  Upload   Total   Spent    Left
 Speed

   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--
 0DEBUG: Fetching archive failed: The requested URL returned error: 404 Not
 Found
 --->  Attempting to fetch libpng-1.6.36_0.darwin_15.x86_64.tbz2 from https
 ://packages-private.macports.org/libpng
   % Total    % Received % Xferd  Average Speed   Time    Time     Time
 Current
                                  Dload  Upload   Total   Spent    Left
 Speed

   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--
 0DEBUG: Fetching archive failed: The requested URL returned error: 404 Not
 Found
 --->  Attempting to fetch libpng-1.6.36_0.darwin_15.x86_64.tbz2 from
 https://packages.macports.org/libpng
   % Total    % Received % Xferd  Average Speed   Time    Time     Time
 Current
                                  Dload  Upload   Total   Spent    Left
 Speed

   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--
 0
   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--
 0DEBUG: Fetching archive failed: The requested URL returned error: 404 Not
 Found
 }}}

 `portfetch::checksites` adds each URL twice: once for use with any tag,
 and then again for the specific tag. Does it need to do that? If so, could
 the list be deduplicated, so that only one copy of each URL remains? Would
 the end of `portfetch::checksites` be a good place to do that
 deduplication, or is it better done elsewhere?

-- 
Ticket URL: <https://trac.macports.org/ticket/57719>
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