You guys are more familiar with the codebase than I am, but it seems to me that the RECORD file should clearly either be not present or empty when metadata has been built but not yet installed. I don't really think the "invalid PEP 376" issue is a problem: PEP 376 describes the metadata for installed distributions; it has nothing to say about built metadata for a distribution which has not yet been installed.

For purposes of the develop command, if a pth file is used to implement develop, then ideally when develop is run a RECORD file would be added containing only the path to that pth file, as thats the only file that has actually been installed (and the only one that should be removed if the develop-installed package is uninstalled).