Add hoft gate to inj stream to prevent inj-only frames from being written to disk

gstlal-ugly/bin/gstlal_ll_inj_stream

@@ -309,6 +309,17 @@ with tempfile.NamedTemporaryFile(mode='w',suffix='.cache') as f:
 				channel_dict[instrument+':'+channel_name] = pipeparts.mkqueue(pipeline, channel_src, max_size_time = Gst.SECOND * 8)
 
 
+		#
+		# Gate inj stream when hoft is not available
+		# this prevents inj-only frames from being written to disk.
+		#
+		hoft_key = list(strain_dict.keys())[0] # hoft strains arrive together
+		gate_hoft_strain = pipeparts.mkqueue(pipeline, strain_dict[hoft_key])
+		inj_strain = pipeparts.mkgate(pipeline, inj_strain, control = gate_hoft_strain, threshold = 0, leaky = True)
+		if options.verbose:
+                    inj_strain = pipeparts.mkprogressreport(pipeline, inj_strain, "%s:inj_strain_after_gate" % (instrument))
+
+
 		#
 		# Combine strains and re-mux
 		#