Accessing CuArrays and CUDAnative through Flux gives `WARNING: replacing module CUDA.` and breaks precompilation

[IanButterworth]

Describe the bug
Within a module/package, accessing CuArrays and CUDAnative through Flux gives WARNING: replacing module CUDA. and breaks precompillation

To Reproduce
The Minimal Working Example (MWE) for this bug:

module Foo
using Flux
using Flux.CuArrays
using Flux.CuArrays.CUDAnative
end

julia> using Foo
[ Info: Precompiling Foo [xxxx]
WARNING: replacing module CUDA.
julia> exit()
...
julia> using Foo
[ Info: Precompiling Foo [xxxx]
WARNING: replacing module CUDA.

Expected behavior
No module replacing and precompillation

Build log
None. Still errors

Environment details (please complete this section)
Details on Julia:

Julia Version 1.3.0-rc5.1
Commit 36c4eb251e (2019-11-17 19:04 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, haswell)
Environment:
  JULIA_NUM_THREADS = 4

Julia packages:
[be33ccc6] CUDAnative v2.5.5 #master (https://github.com/JuliaGPU/CUDAnative.jl.git)
[3a865a2d] CuArrays v1.4.7 #master (https://github.com/JuliaGPU/CuArrays.jl.git)
[587475ba] Flux v0.9.0 #master (https://github.com/FluxML/Flux.jl.git)

CUDA: toolkit and driver version
10.1

Additional context
Add any other context about the problem here.