Fix issue with pack_commands returning an empty byte sequence

Author: jmcbailey

redis/asyncio/connection.py

@@ -922,7 +922,8 @@ def pack_commands(self, commands: Iterable[Iterable[EncodableT]]) -> List[bytes]
  or chunklen > buffer_cutoff
  or isinstance(chunk, memoryview)
  ):
- output.append(SYM_EMPTY.join(pieces))
+ if pieces:
+ output.append(SYM_EMPTY.join(pieces))
  buffer_length = 0
  pieces = []
 

redis/connection.py

@@ -930,7 +930,8 @@ def pack_commands(self, commands):
  or chunklen > buffer_cutoff
  or isinstance(chunk, memoryview)
  ):
- output.append(SYM_EMPTY.join(pieces))
+ if pieces:
+ output.append(SYM_EMPTY.join(pieces))
  buffer_length = 0
  pieces = []