a fix (bug #9881: ALTER TABLE gives wrong error message with sql-mode TRADITIONAL).

sql/field.cc:
  a fix (bug #9881: ALTER TABLE gives wrong error message with sql-mode TRADITIONAL).
  Don't set def if NO_DEFAULT_VALUE_FLAG is set.

mysql-test/r/strict.result

@@ -1235,3 +1235,13 @@ create table t1(a varchar(65537));
 ERROR 42000: Column length too big for column 'a' (max = 65535); use BLOB or TEXT instead
 create table t1(a varbinary(65537));
 ERROR 42000: Column length too big for column 'a' (max = 65535); use BLOB or TEXT instead
+set @@sql_mode='traditional';
+create table t1(a int, b date not null);
+alter table t1 modify a bigint unsigned not null;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` bigint(20) unsigned NOT NULL,
+  `b` date NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;

mysql-test/t/strict.test

@@ -1093,3 +1093,13 @@ set @@sql_mode='traditional';
 create table t1(a varchar(65537));
 --error 1074
 create table t1(a varbinary(65537));
+
+#
+# Bug #9881: problem with altering table
+#
+
+set @@sql_mode='traditional';
+create table t1(a int, b date not null);                                       
+alter table t1 modify a bigint unsigned not null;
+show create table t1;
+drop table t1;

sql/field.cc

@@ -8487,7 +8487,8 @@ create_field::create_field(Field *old_field,Field *orig_field)
   else
     interval=0;
   def=0;
-  if (!old_field->is_real_null() && ! (flags & BLOB_FLAG) &&
+  if (!(flags & NO_DEFAULT_VALUE_FLAG) &&
+      !old_field->is_real_null() && ! (flags & BLOB_FLAG) &&
       old_field->ptr && orig_field)
   {
     char buff[MAX_FIELD_WIDTH],*pos;