Check for gaps in multi-observatory Stream

The method TimeseriesUtility.get_stream_gaps() would over-write gaps[channel] if
there were multiple Traces in a stream that were the same channel, but different
observatories. This is a typical situation when using the AverageAlgorithm.

geomagio/TimeseriesUtility.py

@@ -205,7 +205,10 @@ def get_stream_gaps(stream, channels=None):
         channel = trace.stats.channel
         if channels is not None and channel not in channels:
             continue
-        gaps[channel] = get_trace_gaps(trace)
+        if channel in gaps:
+            gaps[channel].extend(get_trace_gaps(trace))
+        else:
+            gaps[channel] = get_trace_gaps(trace)
     return gaps