tests: adjust error handling

Don't use 'finally' for code that shouldn't run if both normal and
fallback methods failed. Simply move it outside of the 'try' block.

Author: marmarek

tests/test_thunderbird.py

@@ -483,8 +483,7 @@ def receive_message(tb, signed=False, encrypted=False, attachment=None):
         # alternative way of opening 'message security'
         keyCombo('<Control><Alt>s')
         message_security = tb.app.child('Message Security - OpenPGP')
-    finally:
-        message_security = message_security.parent.parent
+    message_security = message_security.parent.parent
     try:
         if signed:
             message_security.child('Good Digital Signature')