don't emit member stat on change during bootstrapping.

ringpop.go

@@ -477,11 +477,16 @@ func (rp *Ringpop) HandleEvent(event events.Event) {
 			}
 			rp.statter.IncCounter(rp.getStatKey("membership-set."+status), nil, 1)
 		}
-		mc, err := rp.CountReachableMembers()
-		if err != nil {
-			rp.logger.Errorf("unable to count members of the ring for statting: %q", err)
-		} else {
-			rp.statter.UpdateGauge(rp.getStatKey("num-members"), nil, int64(mc))
+		// During bootstrapping ringpop is not ready causing errors from
+		// CountReachableMembers. When this is logged it would confuse people
+		// thinking that there is a problem with ringpop bootstrapping
+		if rp.Ready() {
+			mc, err := rp.CountReachableMembers()
+			if err != nil {
+				rp.logger.Errorf("unable to count members of the ring for statting: %q", err)
+			} else {
+				rp.statter.UpdateGauge(rp.getStatKey("num-members"), nil, int64(mc))
+			}
 		}
 		rp.statter.IncCounter(rp.getStatKey("updates"), nil, int64(len(event.Changes)))