fix route-refresh handling

The type of data passed was not what was expected. The reactor
was sending a single type when the API was designed for a list

src/exabgp/reactor/peer.py

@@ -174,8 +174,8 @@ def shutdown(self):
         self._stop("shutting down")
         self.stop()
 
-    def resend(self, enhanced, send_families=None):
-        self.neighbor.rib.outgoing.resend(enhanced, send_families)
+    def resend(self, enhanced, family=None):
+        self.neighbor.rib.outgoing.resend(enhanced, family)
         self._delay.reset()
 
     def reestablish(self, restart_neighbor=None):

src/exabgp/rib/outgoing.py

@@ -69,11 +69,11 @@ def clear(self):
     def pending(self):
         return len(self._new_nlri) != 0 or len(self._refresh_changes) != 0
 
-    def resend(self, enhanced_refresh, families=None):
-        # families can be None or []
-        if not families:
-            families = self.families
-        requested_families = set(families).intersection(self.families)
+    def resend(self, enhanced_refresh, family=None):
+        requested_families = set(self.families)
+
+        if family is not None:
+            requested_families = set(self.families).intersection([family])
 
         if enhanced_refresh:
             for family in requested_families: