Bug #6642 Stored procedure crash if expression with set function

Description:
If a stored procedure contains a SELECT which contains an expression which contains a 
set function (AVG, MIN, SUM, MAX, COUNT), calling the procedure twice causes a crash. 
 

How to repeat:
mysql> create table t (s1 int); 
Query OK, 0 rows affected (0.73 sec) 
 
mysql> create procedure p () select abs(count(s1)) from t; 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> call p(); 
+----------------+ 
| abs(count(s1)) | 
+----------------+ 
|              0 | 
+----------------+ 
1 row in set (0.00 sec) 
 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> call p(); 
ERROR 2006 (HY000): MySQL server has gone away 
No connection. Trying to reconnect... 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket 
'/tmp/mysql.sock' (111) 
ERROR: 
Can't connect to the server

Back trace:

(gdb) bt
#0  0xb7cefa21 in kill () from /lib/libc.so.6
#1  0xb7e4a051 in pthread_kill () from /lib/libpthread.so.0
#2  0xb7e4a42b in raise () from /lib/libpthread.so.0
#3  0xb7cef7b4 in raise () from /lib/libc.so.6
#4  0xb7cf0c7d in abort () from /lib/libc.so.6
#5  0xb7ce8def in __assert_fail () from /lib/libc.so.6
#6  0x08184cd9 in mysql_parse (thd=0x8d34ad8, inBuf=0x8d417d0 "call p()", length=8) at sql_parse.cc:4614
#7  0x0817dadf in dispatch_command (command=COM_QUERY, thd=0x8d34ad8, packet=0x8d2c369 "", packet_length=9)
    at sql_parse.cc:1503
#8  0x0817d498 in do_command (thd=0x8d34ad8) at sql_parse.cc:1311
#9  0x0817c9fa in handle_one_connection (arg=0x8d34ad8) at sql_parse.cc:1047
#10 0xb7e4714b in pthread_start_thread () from /lib/libpthread.so.0
#11 0xb7e471df in pthread_start_thread_event () from /lib/libpthread.so.0
#12 0xb7d7a50a in clone () from /lib/libc.so.6