# Buggy code
async def update(self) -> (str, str):
    """Update the current branch of this repo.

    Returns
    -------
    `tuple` of `str`
        :py:code`(old commit hash, new commit hash)`

    """
    curr_branch = await self.current_branch()
    old_commit = await self.current_commit(branch=curr_branch)

    await self.hard_reset(branch=curr_branch)

    p = await self._run(self.GIT_PULL.format(path=self.folder_path).split())

    if p.returncode != 0:
        raise UpdateError(
            "Git pull returned a non zero exit code"
            " for the repo located at path: {}".format(self.folder_path)
        )

    new_commit = await self.current_commit(branch=curr_branch)

    self._update_available_modules()
    self._read_info_file()

    return old_commit, new_commit


# Traceback (UnicodeDecodeError)
Task exception was never retrieved
future: <Task finished coro=<RepoManager._load_repos() done, defined at /home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/repo_manager.py:618> exception=UnicodeDecodeError('utf-8', b"\x01D\xc79\x12b\x9e\xd6\xa4\xb8\x13\x93TDR \xe3w\xd3@\xc4H$H=2\x0e48\xac\xa6V\xb2\xb3\x19\x1cu\xe9\xed\xae'\xac\xb2\xe7!j\xc7^\xb1\xca\xe2\xa6\xd8\xa8\x9e\xd8\xad\x95\xe6\xa7v)\x9a\x81\xef\xdc\xa2h\x9c~\xba&amp;\xc6G\x1d\x1c\x80\xc3\x10\xd7\xda\x96\xc7\x885$\xc0,\xb3\x12\x18\x89\xec\xb5\xa9e\x8ax1\x91\xc7\\\xa2\x04\x879\x14\xc3\x8a\xcaek*\xda\x9d\xda&amp;\xc6G\x1dL\x01\x92\xc6G\x1dr\x89\xa2r:$z", 2, 3, 'invalid continuation byte')>
Traceback (most recent call last):
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/repo_manager.py", line 621, in _load_repos
ret[folder.stem] = await Repo.from_folder(folder)
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/repo_manager.py", line 487, in from_folder
repo._update_available_modules()
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/repo_manager.py", line 153, in _update_available_modules
curr_modules.append(Installable(location=self.folder_path / name))
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/installable.py", line 68, in __init__
super().__init__(location)
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/json_mixins.py", line 18, in __init__
self._read_info_file()
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/installable.py", line 125, in _read_info_file
super()._read_info_file()
File "/home/aikaterna/v3/lib/python3.6/site-packages/redbot/cogs/downloader/json_mixins.py", line 28, in _read_info_file
info = json.load(f)
File "/usr/lib/python3.6/json/__init__.py", line 296, in load
return loads(fp.read(),
File "/home/aikaterna/v3/lib/python3.6/codecs.py", line 321, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc7 in position 2: invalid continuation byte

# Fixed code
async def update(self) -> (str, str):
    """Update the current branch of this repo.

    Returns
    -------
    `tuple` of `str`
        :py:code`(old commit hash, new commit hash)`

    """
    curr_branch = await self.current_branch()
    old_commit = await self.current_commit(branch=curr_branch)

    await self.hard_reset(branch=curr_branch)

    p = await self._run(self.GIT_PULL.format(path=self.folder_path).split())

    if p.returncode != 0:
        raise errors.UpdateError(
            "Git pull returned a non zero exit code"
            " for the repo located at path: {}".format(self.folder_path)
        )

    new_commit = await self.current_commit(branch=curr_branch)

    self._update_available_modules()
    self._read_info_file()

    return old_commit, new_commit