They were lost during migration from filesystem based constraint.

Changing field name in the form means that the field itself should also be
renamed.

For example, on Mandriva, if SECURE_TMP is enabled (in /etc/security/shell),
then TMP/TMPDIR are set to $HOME/tmp but $HOME is only accessible by the owner
and its group, but not slap user, then the extends-cache temporary directory
will not be accessible after dropping the privileges.

It will reduce execution time.