Always execute session setup

Even if session already exists, if we explicitly pass along a session
file, we should execute it.

.local/bin/tm

@@ -93,9 +93,10 @@ _attach_or_create() {
   # first create a new session if one doesn't exist
   if ! _session_exists; then
     _create_detached_session
-    _load_session_file
   fi
 
+  _load_session_file
+
   # then attach or switch to the session
   if _not_in_tmux; then
     $start attach -t "$session_name"