CQLv2 correctly compiles equality comparisons with NULL into the appropriate expression at runtime. In CQLv1, executing
A={null}, {[A], foo :: [a-A]}
would never succeed, regardless of the value of foo.a. This is no
longer the case: If A is {null} then this will execute as SELECT .... WHERE a IS NULL
and if A is not {null}, it will execute as SELECT .... WHERE a = ?
See the section Removing null comparisions for the dealing with the common requirement to ignore comparisons with null.