cabal: Fix sphinx bug in User Manual creation

* See: https://trac.macports.org/ticket/66680#comment:12

lang/cabal/Portfile

@@ -4,7 +4,7 @@ PortSystem          1.0
 
 name                cabal
 version             3.8.1.0
-revision            1
+revision            2
 categories          lang haskell devel
 platforms           darwin
 license             BSD
@@ -148,6 +148,13 @@ if {${name} eq ${subport}} {
         delete ${haskell_cabal.cabal_root}/bin/ghc-pkg
     }
 
+    # https://trac.macports.org/ticket/66680#comment:12
+    # please remove afer this this sphinx issue is fixed:
+    # https://github.com/haskell/cabal/issues/8681
+    # diff -NaurdwB ./cabal-orig/doc/conf.py ./cabal-new/doc/conf.py | sed -E -e 's/\.\/cabal-(orig|new)/\./' | sed -E -e 's|/opt/local|@PREFIX@|g' > ~/Downloads/patch-doc_conf_py.diff
+    patchfiles-append \
+                    patch-doc_conf_py.diff
+
     haskell_cabal.env \
                     "CABAL_CONFIG=${haskell_cabal.cabal_root}/config" \
                     "GHC=${prefix}/bin/ghc"
@@ -183,6 +190,7 @@ if {${name} eq ${subport}} {
 }
 
 subport cabal-prebuilt {
+    revision        1
     supported_archs arm64 x86_64
 
     use_configure   no

lang/cabal/files/patch-doc_conf_py.diff

@@ -0,0 +1,19 @@
+--- ./doc/conf.py	2023-01-15 15:54:29
++++ ./doc/conf.py	2023-01-15 15:57:09
+@@ -28,12 +28,12 @@
+
+ # extlinks -- see http://www.sphinx-doc.org/en/stable/ext/extlinks.html
+ extlinks = {
+-    'issue': ('https://github.com/haskell/cabal/issues/%s', '#'),
++    'issue': ('https://github.com/haskell/cabal/issues/%s', '#%s'),
+
+-    'ghc-wiki': ('https://gitlab.haskell.org/ghc/ghc/-/wikis/%s', ''),
+-    'ghc-ticket': ('https://gitlab.haskell.org/ghc/ghc/-/issues/%s', 'GHC #'),
++    'ghc-wiki': ('https://gitlab.haskell.org/ghc/ghc/-/wikis/%s', None),
++    'ghc-ticket': ('https://gitlab.haskell.org/ghc/ghc/-/issues/%s', 'GHC #%s'),
+
+-    'hackage-pkg': ('http://hackage.haskell.org/package/%s', ''),
++    'hackage-pkg': ('http://hackage.haskell.org/package/%s', None),
+ }
+
+ # General information about the project.