Qt5Agg backend does not work on windows

[musm]

In my matplotlibrc I have
backend : Qt5Agg

Plotting in Python works fine.

julia> versioninfo()
Julia Version 0.6.0-dev.1636
Commit 99b6a8c* (2016-12-20 13:46 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Core(TM) i7-4510U CPU @ 2.00GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.7.1 (ORCJIT, haswell)

julia>  using PyCall; PyCall.pyprogramname
INFO: Recompiling stale cache file C:\Users\Mus\.julia\lib\v0.6\PyCall.ji for module PyCall.
"C:\\Anaconda3\\python.exe"

julia> PyDict(pyimport("matplotlib")["rcParams"])["backend"]
"Qt5Agg"

julia> using PyPlot
INFO: Recompiling stale cache file C:\Users\Mus\.julia\lib\v0.6\PyPlot.ji for module PyPlot.

julia>  plot(randn(10))
This application failed to start because it could not find or load the Qt platform plugin "windows"
in "".

Reinstalling the application may fix this problem.

[musm]

I no longer get this error but instead a runtime exception
superseeded by #272