Fix mix executable

Author: José Valim

bin/mix

@@ -13,5 +13,5 @@ SELF=$(readlink_f "$0")
 SCRIPT_PATH=$(dirname "$SELF")
 ERL_OPTS=""
 
-if [ "$1" == "iex" ]; then ERL_OPTS="-user Elixir-IEx-CLI -iex wait true"; fi
+if [ "$1" = "iex" ]; then ERL_OPTS="-user Elixir-IEx-CLI -iex wait true"; fi
 exec "$SCRIPT_PATH"/elixir --erl "$ERL_OPTS" -e "Mix.start; Mix.CLI.run" -- "$@"