dht/query: err return NotFound case

When some queries finished, but we got no result, it should
be a simple NotFoundError. Only when every single query ended
in error do we externalize those to the client, in case
something major is going wrong

routing/dht/ext_test.go

@@ -49,6 +49,10 @@ func TestGetFailures(t *testing.T) {
 	// u.POut("Timout Test\n")
 	ctx1, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
 	if _, err := d.GetValue(ctx1, u.Key("test")); err != nil {
+		if merr, ok := err.(u.MultiErr); ok && len(merr) > 0 {
+			err = merr[0]
+		}
+
 		if err != context.DeadlineExceeded {
 			t.Fatal("Got different error than we expected", err)
 		}
@@ -86,6 +90,9 @@ func TestGetFailures(t *testing.T) {
 	ctx2, _ := context.WithTimeout(context.Background(), 20*time.Second)
 	_, err = d.GetValue(ctx2, u.Key("test"))
 	if err != nil {
+		if merr, ok := err.(u.MultiErr); ok && len(merr) > 0 {
+			err = merr[0]
+		}
 		if err != routing.ErrNotFound {
 			t.Fatalf("Expected ErrNotFound, got: %s", err)
 		}
@@ -202,6 +209,9 @@ func TestNotFound(t *testing.T) {
 	v, err := d.GetValue(ctx, u.Key("hello"))
 	log.Debugf("get value got %v", v)
 	if err != nil {
+		if merr, ok := err.(u.MultiErr); ok && len(merr) > 0 {
+			err = merr[0]
+		}
 		switch err {
 		case routing.ErrNotFound:
 			//Success!

routing/dht/query.go

@@ -62,7 +62,7 @@ type dhtQueryRunner struct {
 	peersRemaining todoctr.Counter  // peersToQuery + currently processing
 
 	result *dhtQueryResult // query result
-	errs   []error         // result errors. maybe should be a map[peer.ID]error
+	errs   u.MultiErr      // result errors. maybe should be a map[peer.ID]error
 
 	rateLimit chan struct{} // processing semaphore
 	log       eventlog.EventLogger
@@ -122,8 +122,12 @@ func (r *dhtQueryRunner) Run(peers []peer.ID) (*dhtQueryResult, error) {
 		r.RLock()
 		defer r.RUnlock()
 
-		if len(r.errs) > 0 {
-			err = r.errs[0] // take the first?
+		err = routing.ErrNotFound
+
+		// if every query to every peer failed, something must be very wrong.
+		if len(r.errs) > 0 && len(r.errs) == r.peersSeen.Size() {
+			log.Debugf("query errs: %s", r.errs)
+			err = r.errs[0]
 		}
 
 	case <-r.cg.Closed():