added check for world update to EmergeLog

pym/calculate/lib/utils/portage.py

@@ -1164,6 +1164,14 @@ class EmergeLog():
             if m:
                 self._remove_list.append(m.group(2))
 
+    def did_update_world_happen(self):
+        latest_log = '\n'.join(line for line in self._get_last_changes())
+        reg_emerge = r"(?s)(?<=[\s|@]world\n).*?(?=terminating)"
+        reg_success = r"\w*(?=\:  \*\*\* exiting successfully)"
+        matches = re.finditer(reg_emerge, latest_log)
+        match_successes = [re.search(reg_success, match.group()) for match in matches]
+        return any(match_successes)
+
     def _set_marker(self, text_marker):
         with open(self.emerge_log, 'a') as f:
             f.write("{0:.0f}: {1}\n".format(time.time(), text_marker))