Revert "show/check Homebrew branch"

Library/Homebrew/diagnostic.rb

@@ -519,17 +519,6 @@ module Homebrew
         examine_git_origin(repo, Homebrew::EnvConfig.brew_git_remote)
       end
 
-      def check_brew_git_branch
-        repo = HOMEBREW_REPOSITORY.dup.extend(GitRepositoryExtension)
-        return if repo.git_default_origin_branch?
-
-        <<~EOS
-          Homebrew is not on the default git origin branch and may not receive
-          updates. If this is a surprise to you, check out the default branch with:
-            git -C $(brew --repo) checkout #{repo.git_origin_branch}"
-        EOS
-      end
-
       def check_coretap_integrity
         coretap = CoreTap.instance
         unless coretap.installed?

Library/Homebrew/system_config.rb

@@ -52,11 +52,6 @@ module SystemConfig
       homebrew_repo.git_origin || "(none)"
     end
 
-    sig { returns(String) }
-    def branch
-      homebrew_repo.git_branch || "(none)"
-    end
-
     sig { returns(String) }
     def core_tap_head
       CoreTap.instance.git_head || "(none)"
@@ -160,7 +155,6 @@ module SystemConfig
       f.puts "ORIGIN: #{origin}"
       f.puts "HEAD: #{head}"
       f.puts "Last commit: #{last_commit}"
-      f.puts "Branch: #{branch}"
     end
 
     def homebrew_env_config(f = $stdout)