deepcopy bug in UnionAll types

[ekinakyurek]

Possible bug in deepcopy

julia> x = Array{Float32}
Array{Float32,N} where N

julia> x.var == x.body.parameters[2]
true

julia> x.var
N

julia> y = deepcopy(x)
Array{Float32,N} where N

julia> y == Array{Float32}
true

julia> y = deepcopy(Array{Float32,N} where N)
Array{Float32,N} where N

julia> y == Array{Float32} # !!!
false

julia> y.var == y.body.parameters[2]
false

julia> y.var
N

julia> y.body.parameters[2]
N

julia> versioninfo()
Julia Version 1.1.0
Commit 80516ca202 (2019-01-21 21:24 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin14.5.0)
  CPU: Intel(R) Core(TM) i5-5257U CPU @ 2.70GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, broadwell)