What does a "Could not find .egg-info directory in install record" from pip mean?

Question

Since updating the the most recent setuptools (6.0.1) I get an warning (yellow)

Could not find .egg-info directory in install record for ...

for all the packages I've updated. For example, when updating Twisted I get

Could not find .egg-info directory in install record for Twisted from https://pypi.python.org/packages/source/T/Twisted/Twisted-14.0.2.tar.bz2#md5=.... in /Library/Python/2.7/site-packages

The package updates seems to succeed, however.

What does this warning mean? What can I do to respond to it?

Answer 1

For me upgrading setuptools did not work, what did work was updating pip:

pip install --upgrade setuptools pip

(I've included setuptools too to handle both problems)

Answer 2

This appears to have been a bug introduced in 6.0.1, fixed in setuptools 6.0.2.