The most likely cause is that some code was updated to use pycache directories but other code that computes paths still uses the old way; this happened for bdist_wininst too.  I’ll have a look at the code and reply to your questions tomorrow.  I’ll also add links to another bug where I suggest to print the full command when distutils.spawn fails and DISTUTILS_DEBUG is set and another bug about rpm vs. rpmbuild.

this-job-thing-really-takes-much-of-my-Python-time-ly yours