remove usages of StopIteration to remove warnings on py3

this was due to pep479

disco/bot/bot.py

@@ -275,7 +275,7 @@ class Bot(LoggingClass):
                 mention_rules.get('role', False) and any(mention_roles),
                 msg.channel.is_dm
             )):
-                raise StopIteration
+                return
 
             if mention_direct:
                 if msg.guild:
@@ -296,12 +296,12 @@ class Bot(LoggingClass):
             content = content.lstrip()
 
         if prefix and not content.startswith(prefix):
-            raise StopIteration
+            return
         else:
             content = content[len(prefix):]
 
         if not self.command_matches_re or not self.command_matches_re.match(content):
-            raise StopIteration
+            return
 
         for command in self.commands:
             match = command.compiled_regex.match(content)

disco/types/channel.py

@@ -432,7 +432,7 @@ class MessageIterator(object):
                 limit=self.chunk_size)
 
         if not len(self._buffer):
-            raise StopIteration
+            return
 
         self.after = None
         self.before = None

disco/util/functional.py

@@ -17,7 +17,7 @@ def take(seq, count):
     for _ in range(count):
         i = next(seq, NO_MORE_SENTINEL)
         if i is NO_MORE_SENTINEL:
-            raise StopIteration
+            return
         yield i
 
 

disco/util/paginator.py

@@ -20,7 +20,7 @@ class Paginator(object):
         result = self.func(*self.args, **self.kwargs)
 
         if not len(result):
-            raise StopIteration
+            return
 
         self._buffer.extend(result)
         self._after = self._key(result[-1])

disco/voice/playable.py

@@ -183,7 +183,7 @@ class YoutubeDLInput(FFmpegInput):
 
         if 'entries' not in info:
             yield cls(ie_info=info, *args, **kwargs)
-            raise StopIteration
+            return
 
         for item in info['entries']:
             yield cls(ie_info=item, *args, **kwargs)