confused about DBD implementation of ChopBlanks

Sorry if this turns out to be gibberish but I'm been battling with a 
host of unicode problems today and I am quickly losing track.

I can't make ChopBlanks work properly in DBD::ODBC. It works if I use:

$dbh->{ChopBlanks} = 1;
$sth = $dbh->prepare(q/select * from sometable/);

and does not work if I use:

$sth = $dbh->prepare(q/select * from sometable/);
$sth->{ChopBlanks} = 1;

and it seems "ChopBlanks = DBIc_has(imp_sth, DBIcf_ChopBlanks);" is not 
true in DBD::ODBC's dbdimp.c.

Various DBD's use DBIc_has (DBD::ODBC, DBD::Pg, DBD::Oracle) or DBIc_is 
(DBD::mysql).

The DBI::DBD documentation says (for XS):

"Note that you can also obtain standard attributes such as /AutoCommit/ 
and /ChopBlanks/ from the attributes parameter, using 
|DBD_ATTRIB_GET_IV| for integer attributes."

and

"The dbd_db_STORE_attrib method
You do not handle all attributes; on the contrary, you should not handle 
DBI attributes here: leave this to DBI. (There are two exceptions, 
/AutoCommit/ and /ChopBlanks/, which you should care about.)"

I presumed a DBD should "care" about ChopBlanks as DBI is not going to 
remove the trailing blanks not that DBI is not going to store the 
ChopBlanks value and yet when I call DBIc_has(imp_sth, DBIcf_ChopBlanks) 
on a sth it returns false even though I set $sth->{ChopBlanks} = 1.

DBD::ODBC (like all the other DBDs I've checked) does not handle 
ChopBlanks in the STORE or FETCH routines.

Any ideas what is wrong?

Thanks

Martin