@XTreak / @mariocj89 - can you see any problems with this?
@XTreak: thought you were a core developer now? If so, any ideas why I can't assign you as a reviewer for this?

My username in GitHub is @tirkarthi :) Regarding the __version__ value I think it's left as it is when mock was merged to stdlib in Python 3. There is an open issue around removing __version__ for standard library at https://bugs.python.org/issue31826 and there are several notes like library being maintained externally, decimal module having it for standard etc. There are many modules with similar value like argparse that were merged to stdlib. I don't think anyone is using __version__ for this change to be a breakage. I am +0 on this.

rg "__version__ =\s['\"]\d+." Lib | grep -v '/test/'
Lib/imaplib.py:__version__ = "2.58"
Lib/optparse.py:__version__ = "1.5.3"
Lib/cgi.py:__version__ = "2.6"
Lib/argparse.py:__version__ = '1.1'
Lib/unittest/mock.py:__version__ = '1.0'
Lib/tabnanny.py:__version__ = "6"
Lib/ipaddress.py:__version__ = '1.0'
Lib/socketserver.py:__version__ = "0.4"
Lib/re.py:__version__ = "2.2.1"
Lib/_pydecimal.py:__version__ = '1.70'    # Highest version of the spec this complies with
Lib/platform.py:__version__ = '1.0.8'
Lib/logging/__init__.py:__version__ = "0.5.1.2"
Lib/json/__init__.py:__version__ = '2.0.9'
Lib/http/server.py:__version__ = "0.6"
Lib/tkinter/font.py:__version__ = "0.9"
Lib/tkinter/ttk.py:__version__ = "0.3.1"
Lib/ctypes/__init__.py:__version__ = "1.1.0"
Lib/wsgiref/simple_server.py:__version__ = "0.2"
Lib/ctypes/macholib/__init__.py:__version__ = '1.0'