Fix filesystem race condition on mix test suite
Fix filesystem race condition on mix test suite

gfvcastro/elixir,michalmuskala/elixir,kelvinst/elixir,antipax/elixir,elixir-lang/elixir,antipax/elixir,ggcampinho/elixir,ggcampinho/elixir,kelvinst/elixir,beedub/elixir,pedrosnk/elixir,lexmag/elixir,beedub/elixir,pedrosnk/elixir,kimshrier/elixir,lexmag/elixir,joshprice/elixir,gfvcastro/elixir,kimshrier/elixir