Tweak single execution of blocks for BroadcastLogger to accurately ma…

…intain existing semantics when only a single logger is present.

activesupport/lib/active_support/broadcast_logger.rb

@@ -163,9 +163,19 @@ def initialize_copy(other)
 
     private
       def dispatch(method, *args, **kwargs, &block)
-        yield.tap do |result|
-          block = proc { result }
-        end if block_given?
+        if block_given?
+          # Maintain semantics that the first logger yields the block
+          # as normal, but subsequent loggers won't re-execute the block.
+          # Instead, the initial result is immediately returned.
+          called, result = false, nil
+          block = proc { |*args, **kwargs|
+            if called then result
+            else
+              called = true
+              result = yield(*args, **kwargs)
+            end
+          }
+        end
 
         @broadcasts.map { |logger|
           if logger.respond_to?(method)