enable PQ_NOTIFY_PATCH in config.h

src/include/config.h

@@ -77,5 +77,20 @@ query commands and causes a SIGSEGV trying to execute commands without plan.
 */
 #define FUNC_UTIL_PATCH
 
+/*
+
+Async notifies received while a backend is in the middle of a begin/end
+transaction block are lost by libpq when the final end command is issued.
+
+The bug is in the routine PQexec of libpq. The routine throws away any
+message from the backend when a message of type 'C' is received. This
+type of message is sent when the result of a portal query command with
+no tuples is returned. Unfortunately this is the case of the end command.
+As all async notification are sent only when the transaction is finished,
+if they are received in the middle of a transaction they are lost in the
+libpq library. I added some tracing code to PQexec and this is the output:
+
+*/
+#define PQ_NOTIFY_PATCH
 #endif /* CONFIG_H */