planet: handle response without 'status'

feedparser's parse method returns an arbitrary dictionary which may or
may not have the HTTP status. Rely on get() to return None if it's
lacking and then return and log a message.

planet/management/commands/update_planet.py

@@ -54,15 +54,19 @@ def parse_feed(self, feed_instance):
 
         etag = cache.get(f'planet:etag:{url}')
         feed = feedparser.parse(url, etag=etag)
+        http_status = feed.get('status')
 
-        if feed['status'] == 304:
+        if not http_status:
+            logger.info("The feed '%s' returns no HTTP status", url)
+
+        if http_status == 304:
             logger.info("The feed '%s' has not changed since we last checked it", url)
             if 'etag' in feed:
                 cache.set(f'planet:etag:{url}', feed.etag, 86400)
             return
 
-        if feed['status'] != 200:
-            logger.info("error parsing feed: '%s', status: '%s'", url, feed['status'])
+        if http_status != 200:
+            logger.info("error parsing feed: '%s', status: '%s'", url, http_status)
             return
 
         if not feed.entries: