Fix mix shell tests when ansi escapes are disabled
Fix mix shell tests when ansi escapes are disabled

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