support shortened RFC 822 dates

lib/util/datetime.dart

@@ -1,15 +1,18 @@
 import 'package:intl/intl.dart';
 
-var rfc822DateFormat = DateFormat('EEE, dd MMM yyyy HH:mm:ss Z', 'en_US');
+const rfc822DatePattern = 'EEE, dd MMM yyyy HH:mm:ss Z';
 
 DateTime parseDateTime(dateString) {
   if (dateString == null) return null;
   return _parseRfc822DateTime(dateString) ?? _parseIso8601DateTime(dateString);
 }
 
-DateTime _parseRfc822DateTime(dateString) {
+DateTime _parseRfc822DateTime(String dateString) {
   try {
-    return rfc822DateFormat.parse(dateString);
+    final length = dateString?.length?.clamp(0, rfc822DatePattern.length);
+    final trimmedPattern = rfc822DatePattern.substring(0, length); //Some feeds use a shortened RFC 822 date, e.g. 'Tue, 04 Aug 2020'
+    final format = DateFormat(trimmedPattern, 'en_US');
+    return format.parse(dateString);
   } on FormatException {
     return null;
   }