problem with CI upgrade: active record

[eluser]mohrt[/eluser]
upgrading CI (1.3.1 -> 1.7.2) I have some where clauses like so:

Code:

$this->db->where('vi.member_id=m.id');

that now (incorrectly) get compiled to:

Code:

AND `vi`.`member_id=m`.`id`

bug or feature? this change fixes the compile:

Code:

$this->db->where('vi.member_id','m.id');

Must I change all my code? Why is the query protection filter lumping "member_id=m" into a single value?

TIA