Cannot filter over PersistentVector{Tuple{T,U}}

[hessammehr]

a = PersistentVector([(1,2), (3,4)])
filter(x->true, a)

Produces the following error on Julia 0.5.1 and nightly: ERROR: MethodError: Cannotconvertan object of type Int64 to an object of type Tuple{Int64,Int64}

The following work just fine:

filter(x->true, [ (1,2), (3,4) ]) # => [(1,2), (3,4)]
filter(x->true, PersistentVector(1,2,3,4))  # => Persistent{Int64}[1, 2, 3, 4]