datafind.py: check if ifo key is in time_bins before accessing the bins

gstlal/python/datafind.py

@@ -159,7 +159,7 @@ class DataCache:
 		elif isinstance(time_bins, segmentlist):
 			time_bins = segmentlistdict({ifo: time_bins for ifo in ifos})
 		else:
-			time_bins = segmentlistdict({ifo: time_bins[ifo] for ifo in ifos})
+			time_bins = segmentlistdict({ifo: time_bins[ifo] for ifo in ifos if ifo in time_bins})
 
 		# generate the cache
 		cache = []