MB-11458 upr client should crash if any fatal errors happen

upr client should not supress any erlang process crash that is happening
to the receive worker and try restarting receive worker. The receive
worker process should be restarted only if the upr connection is dropped.

Change-Id: I3815247c9981dfeb9af51deced0ac1dffda05257
Reviewed-on: http://review.couchbase.org/38470
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: buildbot <build@couchbase.com>

src/couch_upr/src/couch_upr_client.erl

@@ -473,10 +473,15 @@ handle_info({stream_event, RequestId, Event}, State) ->
         {noreply, State}
     end;
 
-handle_info({'EXIT', Pid, _Reason}, #state{worker_pid = Pid} = State) ->
+handle_info({'EXIT', Pid, {conn_error, Reason}}, #state{worker_pid = Pid} = State) ->
+    ?LOG_ERROR("upr client (~p): upr receive worker failed due to reason: ~p."
+        " Restarting upr receive worker...", [self(), Reason]),
     timer:sleep(?UPR_RETRY_TIMEOUT),
     restart_worker(State);
 
+handle_info({'EXIT', Pid, Reason}, #state{worker_pid = Pid} = State) ->
+    {stop, Reason, State};
+
 handle_info({print_log, Pid, ReqId}, State) ->
     #state{
         active_streams = ActiveStreams
@@ -1056,7 +1061,7 @@ receive_worker(Socket, Timeout, Parent, MsgAcc0) ->
             receive_worker(Socket, Timeout, Parent, MsgAcc)
         end;
     {error, Reason} ->
-        Reason
+        exit({conn_error, Reason})
     end.
 
 % Check if we need to send buffer ack to server and send it