When a build fails, pip automatically removes all the build files. This should not happen, or there should at least be an option to instruct pip to leave it alone. In many cases the build files provide useful info for troubleshooting, which gets lost for no good reason. Currently, if I want to troubleshoot I have to go find the sources, unpack them somewhere, repeat the build process correctly to reproduce the failure - just to recreate something that was already there. I propose to automatically delete the build files ONLY if the build was successful, otherwise warn and inform the user where the build is. On next run of pip the old build could be automatically deleted or left to the user to take care of. Or: provide a flag, say, --keep-build , which would enable users to request the desirable behaviour.