ModuleNotFoundError: No module named 'pip._vendor.packaging'

pip3 install pymysql 시 'ModuleNotFoundError: No module named 'pip._vendor.packaging' 에러

Traceback (most recent call last):
  File "/usr/local/bin/pip3", line 5, in <module>
    from pip._internal.cli.main import main
  File "/usr/local/lib/python3.9/site-packages/pip/_internal/cli/main.py", line 9, in <module>
    from pip._internal.cli.autocompletion import autocomplete
  File "/usr/local/lib/python3.9/site-packages/pip/_internal/cli/autocompletion.py", line 10, in <module>
    from pip._internal.cli.main_parser import create_main_parser
  File "/usr/local/lib/python3.9/site-packages/pip/_internal/cli/main_parser.py", line 8, in <module>
    from pip._internal.cli import cmdoptions
  File "/usr/local/lib/python3.9/site-packages/pip/_internal/cli/cmdoptions.py", line 21, in <module>
    from pip._vendor.packaging.utils import canonicalize_name
 ModuleNotFoundError: No module named 'pip._vendor.packaging'

 

해결방법
> curl -sS https://bootstrap.pypa.io/get-pip.py | sudo python3
> type pip3
> hash -r
> sudo pip3 install pymysql