scmutil: rewrite docstring for filecache The old docstring was incorrect in that it said that subsequent calls perform a stat() and refresh the object if things change. This is not how things work: __get__ populates obj.__dict__[self.sname] with the result of the decorated function and returns this value without validation on subsequent calls, if available. The correct usage of this type is kinda wonky. It would probably benefit from a refactor. But I don't have time to do that right now. But we can change the docstring so others aren't entrapped by its lies (like I was when using repofilecache in a Mozilla extension). Differential Revision: https://phab.mercurial-scm.org/D3943