mypy 0.930 does not install types #11920

Bug Report

In version 0.930, mypy does not install type packages when run with --install-types.

To Reproduce

Run mypy on code that imports a library that has a separate typing package, e.g. dateutil, both with --install-types and without it.

Expected Behavior

The packages (types-python-dateutil in the example above) should be installed. With mypy 0.920 the message (when running mypy --install-types --non-interactive .) looks something like:

Installing missing stub packages:
python -m pip install types-python-dateutil

The behaviour without --install-types behaves as described in the previous section.

Actual Behavior

In version 0.930, running mypy both with and without --install-types is the same:

licensing/logic/license.py:17: error: Library stubs not installed for "dateutil" (or incompatible with Python 3.7)
licensing/logic/license.py:17: note: Hint: "python3 -m pip install types-python-dateutil"
licensing/logic/license.py:17: note: (or run "mypy --install-types" to install all missing stub packages)
licensing/logic/license.py:17: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
licensing/logic/license.py:18: error: Library stubs not installed for "dateutil.relativedelta" (or incompatible with Python 3.7)

Your Environment

• Mypy version used: 0.930
• Mypy command-line flags: --install-types
• Python version used: 3.7
• Operating system and version: Linux Ubuntu impish