Removed wrong bug fix for problem with timestamp and BETWEEN.

Will be properly fixed in 4.1 and 5.0

sql/field.h

@@ -533,7 +533,6 @@ class Field_timestamp :public Field_num {
   enum Item_result result_type () const { return field_length == 8 || field_length == 14 ? INT_RESULT : STRING_RESULT; }
   enum_field_types type() const { return FIELD_TYPE_TIMESTAMP;}
   enum ha_base_keytype key_type() const { return HA_KEYTYPE_ULONG_INT; }
-  enum Item_result cmp_type () const { return INT_RESULT; }
   void store(const char *to,uint length);
   void store(double nr);
   void store(longlong nr);

sql/item_cmpfunc.cc

@@ -354,7 +354,6 @@ void Item_func_between::fix_length_and_dec()
   if (args[0]->type() == FIELD_ITEM)
   {
     Field *field=((Item_field*) args[0])->field;
-    cmp_type=field->cmp_type();
     if (field->store_for_compare())
     {
       if (convert_constant_item(field,&args[1]))