db/utils: optimize if statements

1) dont use len() to test that a list is non-empty
2) only go down the else clause if it's possible to have a valid
   signature.

1 files changed, 2 insertions, 2 deletions

diff --git a/alot/db/utils.py b/alot/db/utils.py
index 06cb021e..29940fd9 100644
--- a/alot/db/utils.py
+++ b/alot/db/utils.py
@@ -44,9 +44,9 @@ def add_signature_headers(mail, sigs, error_msg):
     if isinstance(error_msg, str):
         error_msg = error_msg.decode('utf-8')
 
-    if len(sigs) == 0:
+    if not sigs:
         error_msg = error_msg or u'no signature found'
-    else:
+    elif not error_msg:
         try:
             key = crypto.get_key(sigs[0].fpr)
             for uid in key.uids: