The license() builtin tries to read it and virtualenv tries to copy it.
See https://github.com/pypa/virtualenv/issues/1352
Up until now, the license() builtin juts felt back to:
See https://www.python.org/psf/license/
However it should output the full license text.
Virtualenv ~16.6 warns:
No LICENSE.txt / LICENSE found in source
Technically, it is probably possible to install the package without
%license files, but that would simply resort to the previous noncritical
behavior.
This fix is not critical and hence it doesn't bump release, for easier
backporting to all our Python packages.
46d035d896