This commit solves a couple of issues

1st. Create_field does not have function vers_sys_field() kind of handy
function, second I think Create_field and Field should not divert much , and
Field does have this function.

2nd. Versioning column does not have NOT_NULL_FLAG, since they can never be
null. So I have added NOT_NULL_FLAG.

3rd. Since I added NOT_NULL_FLAG this created one issue , versioning column
of datatype bigint unsigned were getting NO_DEFAULT_VALUE_FLAG. This makes
test like versioning.insert to fail, Reason being If a column gets this
flag if we insert 'default' value it will generate error(that is why ) test
was failing. So now versioning column wont get NO_DEFAULT_VALUE_FLAG flag.

sql/field.cc

@@ -10475,8 +10475,8 @@ bool Column_definition::check(THD *thd)
       TIMESTAMP columns get implicit DEFAULT value when
       explicit_defaults_for_timestamp is not set.
     */
-    if (opt_explicit_defaults_for_timestamp ||
-        !is_timestamp_type())
+    if ((opt_explicit_defaults_for_timestamp ||
+        !is_timestamp_type()) && !vers_sys_field())
     {
       flags|= NO_DEFAULT_VALUE_FLAG;
     }

sql/field.h

@@ -4214,6 +4214,10 @@ class Column_definition: public Sql_alloc,
     length*= charset->mbmaxlen;
     key_length= pack_length;
   }
+  bool vers_sys_field() const
+  {
+    return flags & (VERS_SYS_START_FLAG | VERS_SYS_END_FLAG);
+  }
   void create_length_to_internal_length_bit();
   void create_length_to_internal_length_newdecimal();
 

sql/sql_table.cc

@@ -4206,7 +4206,8 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
         !sql_field->has_default_function() &&
         (sql_field->flags & NOT_NULL_FLAG) &&
         (!sql_field->is_timestamp_type() ||
-         opt_explicit_defaults_for_timestamp))
+         opt_explicit_defaults_for_timestamp)&&
+        !sql_field->vers_sys_field())
     {
       sql_field->flags|= NO_DEFAULT_VALUE_FLAG;
       sql_field->pack_flag|= FIELDFLAG_NO_DEFAULT;

sql/sql_yacc.yy

@@ -6586,7 +6586,7 @@ field_def:
                 my_yyabort_error((ER_VERS_DUPLICATE_ROW_START_END, MYF(0),
                                   "START", field_name.str));
               }
-              lex->last_field->flags|= VERS_SYS_START_FLAG;
+              lex->last_field->flags|= VERS_SYS_START_FLAG | NOT_NULL_FLAG;
               break;
             case 0:
               p= &info.as_row.end;
@@ -6595,7 +6595,7 @@ field_def:
                 my_yyabort_error((ER_VERS_DUPLICATE_ROW_START_END, MYF(0),
                                   "END", field_name.str));
               }
-              lex->last_field->flags|= VERS_SYS_END_FLAG;
+              lex->last_field->flags|= VERS_SYS_END_FLAG | NOT_NULL_FLAG;
               break;
             default:
               /* Not Reachable */