sql errors html encoded twice

The includes/database.(mysql)|(mysqli)|(pgsql) files all report sql errors in a similar fashion e.g.

if (!mysql_errno($active_db)) {
return $result;
}
else {
trigger_error(check_plain(mysql_error($active_db) ."\nquery: ". $query), E_USER_WARNING);
return FALSE;
}

But the error_handler function uses the t() function on the message

So sql errors are always double escaped, this makes them much harder to read and prevents copy-pasting the query - for running directly.

I think that check_plain should not be called in this place - removing this function call works OK for me.