IdDict with array keys is corrupted by serizalization/deserialization

[DrChainsaw]

It does not 'recognize' its own keys after being deserialized:

julia> using Serialization

julia> d = IdDict([1] => 2, [3] => 4)
IdDict{Array{Int64,1},Int64} with 2 entries:
  [1] => 2
  [3] => 4

julia> serialize("d.jls", d)

julia> ds = deserialize("d.jls")
IdDict{Array{Int64,1},Int64} with 2 entries:
  [1] => 2
  [3] => 4

julia> [k in keys(ds) for k in keys(ds)]
2-element Array{Bool,1}:
 false
 false

julia> versioninfo()
Julia Version 1.1.0
Commit 80516ca202 (2019-01-21 21:24 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, haswell)