vfs: copy if EPERM to avoid file stat ambiguity forcibly at closing Now, files (to be truncated) are opened with checkambig=True, only if localrepository caches it. Therefore, straightforward "copy if EPERM" is always reasonable to avoid file stat ambiguity at closing. This patch makes checkambigatclosing close wrapper copy the target file, and advance mtime on it after renaming, if EPERM. This can avoid file stat ambiguity, even if the target file is owned by another (see issue5418 and issue5584 for detail). This patch factors main logic out instead of changing checkambigatclosing._checkambig() directly, in order to reuse it.