Combine two clauses here

(cherry picked from commit d6e1265)

Author: michaelklishin

src/pg_local.erl

@@ -162,9 +162,7 @@ member_died(Ref, Pid) ->
         [{{ref, Ref}, Pid}] ->
             leave_all_groups(Pid);
         %% in case the key has already been removed
-        %% we can perform the lookup using the DOWN message pid
-        [] ->
-            leave_all_groups(Pid);
+        %% we can perform the lookup using the valuee from the DOWN message
         _  ->
             leave_all_groups(Pid)
     end,