Make sure the patch subject isn't None

Add fail object to 'get()' call, simplifying the subject handling.

Signed-off-by: Veronika Kabatova <[email protected]>

sktm/patchwork.py

@@ -868,10 +868,8 @@ def __update_patch_name(self, patch):
         if 'root_comment' in patch:
             # internal RH only: rewrite the original subject line
             msg = email.message_from_string(patch['root_comment']['headers'])
-            subject = msg.get('Subject')
-            if subject is not None:
-                subject = subject.replace('\n\t', ' ').replace('\n', ' ')
-            # TODO What happens when subject is None?
+            subject = msg.get('Subject', '')
+            subject = subject.replace('\n\t', ' ').replace('\n', ' ')
             patch['name'] = stringify(
                 email.header.decode_header(subject)[0][0]
             )