I agree completely that the documentation should be more explicit. The concept of "os.stat signature" is not defined anywhere as far as I can tell. The naive reader (like me) might mistakenly assume that the "os.stat signature" is a "digital signature" (i.e. a hash) of all of os.stat, and in particular that it includes the st_ino.

I would suggest that the documentation be updated to read "If shallow is true, files with the same length, modification time, and mode are taken to be equal."