bdist_wheel should start by cleaning up its build directory
bdist_wheel does not clean up its build directory making it easy to include obsolete/unwanted files.
On python 2.7, if you run
python setup.py bdist_wheel once, add a file in
build/lib.linux-x86_64-2.7 and rerun
python setup.py bdist_wheel you'll have the file in your wheel.
I had this issue with https://github.com/Polyconseil/getconf but it concerns all packages, you can easily reproduce with the wheel package.
It can be quite unsettling, since it bypasses, all MANIFEST or find_packages rules...
It would seem cleaner and safer to simply start from a fresh directory and delete it afterwards.