move is_expected calculation to own function

Just reorganization for clarity

csppfetch/__init__.py

@@ -514,6 +514,10 @@ class Downloader:
             fileset_list_list.append(fileset_list)
         return fileset_list_list
 
+    def is_expected(self, time):
+        if self.expected_newest is None:
+            return False
+        return time < (datetime.datetime.now() - self.expected_newest )
 
     def get_filesets_for_time(self, time):
         """ Return list of FileSets suitable for use at time
@@ -546,9 +550,7 @@ class Downloader:
                 local = self._expand(self.local, time, priority)
                 urls_to_files = {url_relative: local}
 
-                expected = False
-                if self.expected_newest is not None:
-                    expected = time < (datetime.datetime.now() - self.expected_newest )
+                expected = self.is_expected(time)
 
                 priority_desc = f'"{priority}"' if priority != "" else '"" (empty string)'
                 description = f"{self.name} for {time} at priority {priority_desc}"