Bug #10802 Different "explain" output

Description:
Build of 5.0.6, based on ChangeSet
  1.1889 05/05/21 23:23:39 kent@mysql.com +5 -0
  default_modify.c:
    Use MY_STAT to declare argument to my_fstat()
  des_key_file.cc:
    Use local seach path for "mysql_priv.h"
  mysys.dsp, libmysqld.dsp, libmysql.dsp:
    New file needed, "../mysys/default_modify.c"

Test suite failure in "bdb":

-------------------------------------------------------
*** r/bdb.result        Fri May 20 19:02:53 2005
--- r/bdb.reject        Sat May 21 03:31:00 2005
***************
*** 1862,1868 ****
  insert into t1 values (1, 'A'), (20, NULL);
  explain select * from t1 where a=20 and b is null;
  id    select_type     table   type    possible_keys   key     key_len ref     rows    Extra
! 1     SIMPLE  t1      ref     ba      ba      20      const,const     1       Using where
  select * from t1 where a=20 and b is null;
  a     b
  20    NULL
--- 1862,1868 ----
  insert into t1 values (1, 'A'), (20, NULL);
  explain select * from t1 where a=20 and b is null;
  id    select_type     table   type    possible_keys   key     key_len ref     rows    Extra
! 1     SIMPLE  t1      ALL     ba      NULL    NULL    NULL    2       Using where
  select * from t1 where a=20 and b is null;
  a     b
  20    NULL
-------------------------------------------------------

Happens in all three runs ("default", "--ps-protocol", "--embedded-server") for the "max" builds on all HP-PA machines:
- hp3750 (HP-UX 11.00, HP-PA, 32 bit),
- hp3750-64bit (HP-UX 11.00, HP-PA, 64 bit),
- hpux11 (HP-UX 11.11, HP-PA, 32 bit),
- hpux11-64bit (HP-UX 11.11, HP-PA, 64 bit)

How to repeat:
Run the suite.

The test "bdb" is _skipped_ for all builds but "max", so its restriction to "max" builds seems not to signify a connection to NDB.
These builds use the HP compiler.

"max" tree of 5.0.9 is saved on "hpux11" in directory "~/bug10802".

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/28277

Fixed in 5.0.12, cset  1.1975.7.1

Noted in 5.0.12 changelog.