formula_installer: bottle against Homebrew Python.

When Python is required or recommended then always bottle against the
Homebrew provided Python rather than the system one. This will allow
bottling of packages that have a hard dependency on Python bindings
(which can’t be shared between system and Homebrew Pythons).

Closes Homebrew/homebrew#27112.

Library/Homebrew/formula_installer.rb

@@ -58,14 +58,6 @@ class FormulaInstaller
     return true if f.local_bottle_path
     return false unless f.bottle && f.pour_bottle?
 
-    f.requirements.each do |req|
-      next if req.optional? || req.pour_bottle?
-      if install_bottle_options[:warn]
-        ohai "Building source; bottle blocked by #{req} requirement"
-      end
-      return false
-    end
-
     unless f.bottle.compatible_cellar?
       if install_bottle_options[:warn]
         opoo "Building source; cellar of #{f}'s bottle is #{f.bottle.cellar}"
@@ -265,7 +257,8 @@ class FormulaInstaller
             Requirement.prune
           elsif req.build? && dependent != f && install_bottle_for_dep?(dependent, build)
             Requirement.prune
-          elsif req.satisfied?
+          elsif req.satisfied? && !(pour_bottle? || build_bottle?) \
+                && !(!req.optional? && req.default_formula?)
             Requirement.prune
           elsif req.default_formula?
             dep = req.to_dependency