Fix logic for determining frame type in make_skymap (gwastro#4937)

bin/pycbc_make_skymap

@@ -106,14 +106,6 @@ def main(trig_time, mass1, mass2, spin1z, spin2z, f_low, f_upper, sample_rate,
         frame_types = {}
     if channel_names is None:
         channel_names = {}
-    for ifo in ifos:
-        if ifo not in frame_types:
-            frame_types[ifo] = default_frame_type(mean_trig_time, ifo)
-        if ifo not in channel_names:
-            if fake_strain[ifo] is not None:
-                channel_names[ifo] = ifo + ':FAKE_DATA'
-            else:
-                channel_names[ifo] = default_channel_name(mean_trig_time, ifo)
 
     # resulting files will be tagged with this string
     file_name_tag = '{:.0f}'.format(mean_trig_time)
@@ -165,6 +157,12 @@ def main(trig_time, mass1, mass2, spin1z, spin2z, f_low, f_upper, sample_rate,
     st_psd_paths = {}
     st_out_paths = {}
     for ifo in ifos:
+        if ifo not in channel_names:
+            if fake_strain[ifo] is not None:
+                channel_names[ifo] = ifo + ':FAKE_DATA'
+            else:
+                channel_names[ifo] = default_channel_name(mean_trig_time, ifo)
+
         # compose the command line for the single-template process
         st_psd_paths[ifo] = os.path.join(
                 tmpdir, 'PSD_{}_{}.txt'.format(file_name_tag, ifo))
@@ -227,6 +225,8 @@ def main(trig_time, mass1, mass2, spin1z, spin2z, f_low, f_upper, sample_rate,
                 command.append(str(fake_strain_seed[ifo]))
         elif custom_frame_files is None or ifo not in custom_frame_files:
             # use default guesses for this ifo
+            if ifo not in frame_types:
+                frame_types[ifo] = default_frame_type(mean_trig_time, ifo)
             command.append("--frame-type")
             command.append(frame_types[ifo])
         else: