Guarantee no race between ruby server's shutdown_and_notify and destroy

src/ruby/lib/grpc/generic/rpc_server.rb

@@ -244,9 +244,9 @@ module GRPC
         fail 'Cannot stop before starting' if @running_state == :not_started
         return if @running_state != :running
         transition_running_state(:stopping)
-      end
         deadline = from_relative_time(@poll_period)
         @server.shutdown_and_notify(deadline)
+      end
       @pool.stop
     end
 
@@ -416,10 +416,12 @@ module GRPC
         end
       end
       # @running_state should be :stopping here
-      @run_mutex.synchronize { transition_running_state(:stopped) }
+      @run_mutex.synchronize do
+        transition_running_state(:stopped)
         GRPC.logger.info("stopped: #{self}")
         @server.close
       end
+    end
 
     def new_active_server_call(an_rpc)
       return nil if an_rpc.nil? || an_rpc.call.nil?