The fix is for MXAlias: it didn't test what was to be tested: the intended
case is where MX exchange name is an alias:
cnamemx.example.com. MX 10 cnamemailer.example.com.
cnamemailer.example.com. CNAME www.example.com.
(and the test asks for cnamemx.example.com/MX)
but it tested the case where the owner name of MX is an alias
(ask cnamemailer.example.com/MX in the above example).