Revert "fix(vendor-gems): redirect bundler stdout to stderr"

Library/Homebrew/dev-cmd/vendor-gems.rb

@@ -40,7 +40,7 @@ module Homebrew
       end
 
       ohai "bundle install --standalone"
-      safe_system_redirect_stdout_to_stderr "bundle", "install", "--standalone"
+      safe_system "bundle", "install", "--standalone"
 
       ohai "bundle pristine"
       safe_system "bundle", "pristine"

Library/Homebrew/utils.rb

@@ -332,19 +332,6 @@ module Kernel
     end
   end
 
-  # Redirects stdout to stderr, throws exception on command failure.
-  def safe_system_redirect_stdout_to_stderr(cmd, *args)
-    return if Homebrew._system(cmd, *args) do
-      # Redirect stdout stream to stderr stream. This is useful to prevent
-      # subprocesses from writing to stdout and interfering with the intended
-      # output, e.g. when running a brew command with `--json` for programs
-      # automating brew commands.
-      $stdout.reopen($stderr)
-    end
-
-    raise ErrorDuringExecution.new([cmd, *args], status: $CHILD_STATUS)
-  end
-
   def which(cmd, path = ENV["PATH"])
     PATH.new(path).each do |p|
       begin

Library/Homebrew/utils/gems.rb

@@ -144,9 +144,7 @@ module Homebrew
 
       # for some reason sometimes the exit code lies so check the output too.
       if bundle_check_failed || bundle_check_output.include?("Install missing gems")
-        begin
-          safe_system_redirect_stdout_to_stderr bundle, "install"
-        rescue ErrorDuringExecution
+        unless system bundle, "install"
           message = <<~EOS
             failed to run `#{bundle} install`!
           EOS