> I'm not sure what you mean by "using". AFAIK, each distribution's files (recorded in RECORD)
> would be unique to that distribution (else distros like Debian will have problems, since
> files are owned by one package and one package only).
Files need to belong to one distribution only, but directories can be shared by more than one.  In my example, I meant that ProjectX can create the directories a and a/b and the file a/b/thing, then ProjectZ can create the file a/b/otherthing, and if we remove ProjectX and then ProjectZ, a and a/b won’t be in ProjectZ’s RECORD, because they were in ProjectX’s.

Carl: Can you tell us how pip removes directories?

> 1. Record any directories that are created in RECORD, ideally bottom-up.
To solve the problem I mentioned above (hopefully making sense this time :), we’d need to record all directories that would have been created.  It may be hard or even unfeasible to sort “directory that existed before Python was installed”, e.g. /usr/lib/python2.7/site-packages, and “directory created by one project”, e.g. /usr/lib/python2.7/site-packages/somelib.