trunc: catch stopiter

edosl0util/trunc.py

@@ -13,10 +13,16 @@ def trunc_stream(stream, start, end):
         # first pkt in group
         yield pkt
         # following pkts in group
-        pkt = stream.next()
+        try:
+            pkt = stream.next()
+        except StopIteration:
+            return
         while pkt.stamp is None:
             yield pkt
-            pkt = stream.next()
+            try:
+                pkt = stream.next()
+            except StopIteration:
+                return
 
 
 def trunc_file(filename, start, end, stream_impl=jpss_packet_stream):