Fix no estaba mapeando la media cuando venia del cache

fetcher/medium.py

@@ -141,15 +141,20 @@ def map_media(mb_media):
     return media
 
 
-def map_recording(mb_recording):
+def map_recording(mb_recording, artist=True):
     """Mapea el modelo de recording entregado por musicbrainz a uno propio"""
-    return {
+    recording = {
         'id': mb_recording.get('id'),
         'title': mb_recording.get('title'),
         'disambiguation': mb_recording.get('disambiguation'),
         'length': mb_recording.get('length'),
     }
 
+    if artist:
+        recording['artist'] = map_artist_credit(mb_recording.get('artist_credit')[0])
+
+    return recording
+
 
 def map_coverart(mb_cover):
     """Mapea el modelo de coverart entregado por musicbrainz a uno propio"""
@@ -363,7 +368,14 @@ def get_recordings_of_release(mbid):
 
     mb_medias = cache.get_recordings_of_release(mbid)
     if mb_medias:
-        return {'medias': mb_medias}
+        medias = []
+        for media in mb_medias:
+            recordings = []
+            for recording in media.get('recordings'):
+                recordings.append(map_recording(recording))
+            media['recordings'] = recordings
+            medias.append(media)
+        return {'medias': medias}
 
     mb_release = mb.get_release_by_mbid(mbid, ['recordings', 'artist-credits'])