Fixed BUG#4904: Stored procedure crash if continue handler for HY000 errors.

The description is not entirerly correct. The issue was follow-up errors
  where the first error is not caught - in which case it's often a system
  error with errcode < 1000 (which are mapped by default to 'HY000'). In this
  case the error state is different from what was assumed in the execution
  loop.


mysql-test/r/sp.result:
  New test case for BUG#4902.
mysql-test/t/sp.test:
  New test case for BUG#4902.
sql/sp_head.cc:
  Don't test the net.report_error flag in the execution loop. (Don't know
  why this was done in the first place, as it seems to serve no purpose.)

mysql-test/r/sp.result

@@ -2237,6 +2237,14 @@ Tables_in_test (foo)	table_type
 Variable_name	Value
 Level	Code	Message
 drop procedure bug4902|
+drop table if exists t3|
+create procedure bug4904()
+begin
+declare continue handler for sqlstate 'HY000' begin end;
+create table t2 as select * from t;
+end|
+call bug4904()|
+drop procedure bug4904|
 drop table if exists fac|
 create table fac (n int unsigned not null primary key, f bigint unsigned)|
 create procedure ifac(n int unsigned)

mysql-test/t/sp.test

@@ -1717,6 +1717,24 @@ call bug4902()|
 
 drop procedure bug4902|
 
+#
+# BUG#4904
+#
+--disable_warnings
+drop table if exists t3|
+--enable_warnings
+
+create procedure bug4904()
+begin
+  declare continue handler for sqlstate 'HY000' begin end;
+
+  create table t2 as select * from t;
+end|
+
+call bug4904()|
+
+drop procedure bug4904|
+
 
 #
 # Some "real" examples