getindex slice fails with CartesianIndex for v0.5

[davidavdav]

Hello,

In a NamedArrays test I needed cartesian indexing for displaying arrays with ndims()>2. In v0.4 this construction works:

a = rand(2,2,2)
a[:, :, CartesianIndex((1,))]

but in v0.5 (0.5.0-dev+5154) I get

ERROR: MethodError: no method matching _flatten(::Tuple{}, ::Colon, ::Colon, ::CartesianIndex{1})
Closest candidates are:
  _flatten(::Any, ::Integer, ::Any...)
  _flatten(::Any, ::CartesianIndex{N}, ::Any...)
  _flatten(::Any)
 in getindex(::Array{Float64,3}, ::Colon, ::Colon, ::CartesianIndex{1}) at ./abstractarray.jl:701
 in eval(::Module, ::Any) at ./boot.jl:234
 in macro expansion at ./REPL.jl:92 [inlined]
 in (::Base.REPL.##1#2{Base.REPL.REPLBackend})() at ./event.jl:46