Handle when :file.get_cwd returns a binary

Author: José Valim

lib/elixir/lib/file.ex

@@ -884,7 +884,8 @@ defmodule File do
   """
   def cwd() do
     case F.get_cwd do
-      { :ok, cwd } -> { :ok, to_string(cwd) }
+      { :ok, base } when is_binary(base) -> { :ok, base }
+      { :ok, base } -> { :ok, to_string(base) }
       { :error, _ } = error -> error
     end
   end

lib/elixir/lib/path.ex

@@ -243,6 +243,7 @@ defmodule Path do
   """
   def relative_to_cwd(path) do
     case :file.get_cwd do
+      { :ok, base } when is_binary(base) -> relative_to(path, to_char_list(base))
       { :ok, base } -> relative_to(path, base)
       _ -> path
     end

lib/elixir/lib/system.ex

@@ -93,7 +93,8 @@ defmodule System do
   """
   def cwd do
     case :file.get_cwd do
-      { :ok, list } -> String.from_char_list!(list)
+      { :ok, base } when is_binary(base) -> base
+      { :ok, base } -> String.from_char_list!(base)
       _ -> nil
     end
   end