Fix broadcast logger patch

[wpliao1989]

Fix duplicate logging in Rails 7.1+

Summary

• Fixes duplicate log lines caused by Rails 7.1's BroadcastLogger wrapping custom loggers
• Prevents broadcast_to from adding additional log destinations that cause double logging
• Fixes timing issue where the broadcast_to no-op was applied too late (in after_initialize) allowing gems like Sidekiq to add duplicate loggers before the fix was in place

Problem

In Rails 7.1+, the bootstrap process wraps custom loggers (like the logging gem) in an ActiveSupport::BroadcastLogger:

# rails/railties/lib/rails/application/bootstrap.rb
broadcast_logger = ActiveSupport::BroadcastLogger.new(Rails.logger)
Rails.logger = broadcast_logger

Then various components call Rails.logger.broadcast_to() to add additional log destinations:

• Rails server (log_to_stdout) - adds console logger in development
• Rails console - adds STDERR logger
• Sidekiq - adds Sidekiq.logger as a broadcast sink
• ActiveRecord railtie - adds console logger

This causes:

1. Duplicate log lines - each log message is written once per broadcast sink
2. Double block execution - BroadcastLogger#method_missing calls methods like with_context on each sink, executing the block multiple times

Solution

Add an initializer that runs after :initialize_logger (when the BroadcastLogger is created) but before any after_initialize hooks (where Sidekiq and others add their loggers):

initializer 'epilog.prevent_broadcast', after: :initialize_logger do
  if ::Rails.gem_version >= Gem::Version.new('7.1') && ::Rails.logger
    ::Rails.logger.define_singleton_method(:broadcast_to) { |*| nil }
  end
end

This ensures the no-op broadcast_to is in place before any gem can add duplicate destinations.

Timeline Comparison

Before (broken):

1. :initialize_logger → Rails wraps logger in BroadcastLogger
2. after_initialize hooks run:
   - Sidekiq calls broadcast_to → ADDS LOGGER ❌
   - Epilog adds no-op → too late!

After (fixed):

1. :initialize_logger → Rails wraps logger in BroadcastLogger
2. epilog.prevent_broadcast → adds no-op broadcast_to ✓
3. after_initialize hooks run:
   - Sidekiq calls broadcast_to → NO-OP (blocked) ✓