I've just installed Python 3.7.3rc1 for macOS 10.9 or later from the macOS 64-bit installer.

I've clicked the `Install Certificates.command`, which opened a Terminal, ran and failed with:

```
Last login: Mon Mar 18 16:36:21 on ttys010
Welcome to fish, the friendly interactive shell
… ~> /Applications/Python\ 3.7/Install\ Certificates.command ; exit;
 -- pip install --upgrade certifi
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/__main__.py", line 16, in <module>
    from pip._internal import main as _main  # isort:skip # noqa
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/_internal/__init__.py", line 19, in <module>
    from pip._vendor.urllib3.exceptions import DependencyWarning
ModuleNotFoundError: No module named 'pip._vendor.urllib3.exceptions'
Traceback (most recent call last):
  File "<stdin>", line 44, in <module>
  File "<stdin>", line 25, in main
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 347, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['/Library/Frameworks/Python.framework/Versions/3.7/bin/python3.7', '-E', '-s', '-m', 'pip', 'install', '--upgrade', 'certifi']' returned non-zero exit status 1.

[Process completed]
```

I was able to run the same command from my regular shell (iTerm2, fish, $PATH addons, etc.) and that completed just fine and installed certifi==2019.3.9

Either there's just something wrong with my system (what?) or the initial experience for average user is broken (unlikely?)...