fix #437

edge模式，重新从源站拉流时，导致forwarders异常

@@ -94,6 +94,13 @@ int SrsEdgeIngester::initialize(SrsSource* source, SrsPlayEdge* edge, SrsRequest
 
 int SrsEdgeIngester::start()
 {
+    int ret = ERROR_SUCCESS;
+
+    if ((ret = _source->on_publish()) != ERROR_SUCCESS) {
+        srs_error("edge pull stream then publish to edge failed. ret=%d", ret);
+        return ret;
+    }
+
     return pthread->start();
 }
 
@@ -114,7 +121,8 @@ void SrsEdgeIngester::stop()
 int SrsEdgeIngester::cycle()
 {
     int ret = ERROR_SUCCESS;
-    
+    _source->on_source_id_changed(_srs_context->get_id());
+        
     std::string ep_server, ep_port;
     if ((ret = connect_server(ep_server, ep_port)) != ERROR_SUCCESS) {
         return ret;
@@ -144,11 +152,6 @@ int SrsEdgeIngester::cycle()
         return ret;
     }
     
-    if ((ret = _source->on_publish()) != ERROR_SUCCESS) {
-        srs_error("edge pull stream then publish to edge failed. ret=%d", ret);
-        return ret;
-    }
-    
     if ((ret = _edge->on_ingest_play()) != ERROR_SUCCESS) {
         return ret;
     }