Alchemist is using wrong version

[axelson]

I have a similar issue to #282. I am also using Spacemacs and I have (setq alchemist-mix-command "~/.asdf/installs/elixir/1.6.2/bin/mix") set. I do know that it is being picked up because if I set it to an invalid value I get an error when running alchemist-mix-test-at-point. Running alchemist-iex-run and then executing System.version I get "1.6.2" as I expect. However, running an ExUnit test with the contents:

defmodule ExampleTest do
  use ExUnit.Case

  test "Elixir version" do
    IO.inspect(System.version(), label: "System.version()")
  end
end

I get System.version(): "1.6.4" as the output, instead of 1.6.2 as I would expect. Is there anything I can do to debug this issue?