Avoid warning with Elixir 1.3.1

Compiling 2 files (.ex)
warning: the variable "log" is unsafe as it has been set inside a case/cond/receive/if/&&/||. Please explicitly return the variable value instead. For example:

    case int do
      1 -> atom = :one
      2 -> atom = :two
    end

should be written as

    atom =
      case int do
        1 -> :one
        2 -> :two
      end

Unsafe variable found at:
  lib/ex_syslog.ex:35

lib/ex_syslog.ex

@@ -24,12 +24,12 @@ defmodule ExSyslog do
                   %{name: name, log: log, config: config} = state) do
     new_config = get_config(name, options)
 
-    if config.facility !== new_config.facility or
+    {:ok, log} = if config.facility !== new_config.facility or
        config.ident !== new_config.ident or
        config.option !== new_config.option do
 
         close_log(log)
-        {:ok, log} = open_log(new_config)
+        open_log(new_config)
     end
 
     new_state = %{state | log: log, config: new_config}