resource: automatic determine mirrors for PyPI resources

Library/Homebrew/env_config.rb

@@ -318,6 +318,10 @@ module Homebrew
                      "outdated.",
         boolean:     true,
       },
+      HOMEBREW_PIP_INDEX_URL:                    {
+        description:  "If set, `brew install <formula>` will use this URL to download PyPI package resources.",
+        default_text: "`https://pypi.org/simple`.",
+      },
       HOMEBREW_PRY:                              {
         description: "If set, use Pry for the `brew irb` command.",
         boolean:     true,

Library/Homebrew/resource.rb

@@ -294,6 +294,14 @@ class Resource
       end
     end
 
+    # PyPI packages: PEP 503 – Simple Repository API <https://peps.python.org/pep-0503>
+    if Homebrew::EnvConfig.pip_index_url.present?
+      pip_index_base_url = Homebrew::EnvConfig.pip_index_url.chomp("/").chomp("/simple")
+      %w[https://files.pythonhosted.org https://pypi.org].each do |base_url|
+        extra_urls << url.sub(base_url, pip_index_base_url) if url.start_with?("#{base_url}/packages")
+      end
+    end
+
     [*extra_urls, url, *mirrors].uniq
   end
 

Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi

@@ -2655,6 +2655,8 @@ module Homebrew::EnvConfig
 
   def self.no_proxy(); end
 
+  def self.pip_index_url(); end
+
   def self.pry?(); end
 
   def self.simulate_macos_on_linux?(); end