resources: Don't double close on Running restart

If we use the "retry" metaparam on a Watch, we want to avoid a double
close due to the second Running() signal. This avoids this with a simple
flag.

resources/resources.go

@@ -197,6 +197,7 @@ type BaseRes struct {
 	state     ResState
 	working   bool          // is the Worker() loop running ?
 	started   chan struct{} // closed when worker is started/running
+	isStarted bool          // did the started chan already close?
 	starter   bool          // does this have indegree == 0 ? XXX: usually?
 	isStateOK bool          // whether the state is okay based on events or not
 	isGrouped bool          // am i contained within a group?

resources/sendrecv.go

@@ -108,8 +108,11 @@ func (obj *BaseRes) Running(processChan chan *event.Event) error {
 		cuid.SetConverged(true) // a reasonable initial assumption
 	}
 
-	obj.StateOK(false) // assume we're initially dirty
-	close(obj.started) // send started signal
+	obj.StateOK(false)  // assume we're initially dirty
+	if !obj.isStarted { // this avoids a double close when/if watch retries
+		obj.isStarted = true
+		close(obj.started) // send started signal
+	}
 
 	var err error
 	if obj.starter { // vertices of indegree == 0 should send initial pokes