pytweening 1.0.5 breaks python2.7 install

Expected: python2.7 pip successfully installs pytweening 1.0.5

Actual: python2.7 pip successfully installs broken `UNKNOWN` package

Repro:

```bash
$ python2.7 -m virtualenv tmp27
$ tmp27/bin/pip install 'pytweening==1.0.5' && tmp27/bin/python -c "import pytweening"
DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support pip 21.0 will remove support for this functionality.
Looking in indexes: https://artifactory.cam.displaylink.com/artifactory/api/pypi/dl-pypi/simple
Collecting pytweening==1.0.5
Using cached https://xxxx/artifactory/api/pypi/dl-pypi/packages/packages/19/f7/0b05178d04da07517ac29de583cf795e545f005be4fbbf8decd0a75f2a23/pytweening-1.0.5.tar.gz (168 kB)
Installing build dependencies ... done
Getting requirements to build wheel ... done
Installing backend dependencies ... done
Preparing wheel metadata ... done
WARNING: Generating metadata for package pytweening produced metadata for project name unknown. Fix your #egg=pytweening fragments.
Building wheels for collected packages: unknown, unknown
Building wheel for unknown (PEP 517) ... done
Created wheel for unknown: filename=UNKNOWN-0.0.0-py2-none-any.whl size=2464 sha256=5fd3d428d7169e76e9ab80e0d3e7b3de26de839d77c22b74b6e51587f8992071
Stored in directory: /home/gnome/.cache/pip/wheels/9f/3f/9c/f06cd1621a45e83b5971f37fbf548133452bf08d07a7ff81b9
Building wheel for unknown (PEP 517) ... done
Created wheel for unknown: filename=UNKNOWN-0.0.0-py2-none-any.whl size=2464 sha256=5fd3d428d7169e76e9ab80e0d3e7b3de26de839d77c22b74b6e51587f8992071
Stored in directory: /home/gnome/.cache/pip/wheels/89/3a/3c/408440ab2f6f9b99a9c6fa94ff7331044c9f07392eeeea14a7
Successfully built unknown unknown
Installing collected packages: unknown
Successfully installed unknown-0.0.0

Traceback (most recent call last):
File "", line 1, in
ImportError: No module named pytweening
```

```bash
$ tmp27/bin/pip list
Package Version
---------- -------
pip 20.3.4
setuptools 44.1.1
UNKNOWN 0.0.0
wheel 0.37.1
```

No source file or test is named. Start by reproducing the Python 2.7 virtualenv and pip install command from the issue, then inspect the package's installation metadata and build output. Done means pip installs pytweening 1.0.5 under Python 2.7 and `import pytweening` succeeds instead of producing UNKNOWN-0.0.0.

Written by the indexing model from the issue text.