pip unable to find an extension of a lib.

[dieter]

Vincent Vande Vyvre <vincent.vande.vyvre at telenet.be> writes:
> ...
> Using Python-3.7.2 (compiled with --with-pydebug) in a venv, I've
> encountered this problem:
>
> $ pip install --upgrade pip setuptools wheel
> ....
> Successfully installed setuptools-41.0.0 wheel-0.33.1
> -------------------------------
> ...
> $ pip install pyqt5
> ...
> Collecting PyQt5_sip<4.20,>=4.19.14 (from pyqt5)
>   Could not find a version that satisfies the requirement
> PyQt5_sip<4.20,>=4.19.14 (from pyqt5) (from versions: )
> No matching distribution found for PyQt5_sip<4.20,>=4.19.14 (from pyqt5)
> ...
> $ pip search pyqt5
> ...
> PyQt5-sip (4.19.15)               - Python extension module support

There is a spelling difference: "PyQt5_sip" versus "PyQt5-sip" --
not sure, however, whether this is important.