CoreTap.default_remote: Use Linuxbrew/core [Linux]

Library/Homebrew/cmd/update.sh

@@ -24,7 +24,12 @@ git() {
 
 git_init_if_necessary() {
   BREW_OFFICIAL_REMOTE="https://github.com/Homebrew/brew"
-  CORE_OFFICIAL_REMOTE="https://github.com/Homebrew/homebrew-core"
+  if [[ -n "$HOMEBREW_MACOS" ]] || [[ -n "$HOMEBREW_FORCE_HOMEBREW_ORG" ]]
+  then
+    CORE_OFFICIAL_REMOTE="https://github.com/Homebrew/homebrew-core"
+  else
+    CORE_OFFICIAL_REMOTE="https://github.com/Linuxbrew/homebrew-core"
+  fi
 
   safe_cd "$HOMEBREW_REPOSITORY"
   if [[ ! -d ".git" ]]

Library/Homebrew/extend/os/linux/tap.rb

+class CoreTap < Tap
+  def default_remote
+    if ENV["HOMEBREW_FORCE_HOMEBREW_ORG"]
+      "https://github.com/Homebrew/homebrew-core".freeze
+    else
+      "https://github.com/Linuxbrew/homebrew-core".freeze
+    end
+  end
+end

Library/Homebrew/extend/os/tap.rb

+require "extend/os/linux/tap" if OS.linux?

Library/Homebrew/tap.rb

@@ -735,3 +735,5 @@ class TapConfig
     end
   end
 end
+
+require "extend/os/tap"