lazymanifest: make __iter__ generate filenames, not 3-tuples The _lazymanifest type(s) behave very much like a sorted dict with filenames as keys and (nodeid, flags) as values. It therefore seems surprising that its __iter__ generates 3-tuples of (path, nodeid, flags). Let's make it match dict's behavior of generating the keys instead, and add a new iterentries method for the 3-tuples. With this change, the "x" in "if x in lm" and "for x in lm" now have the same type (a filename string).