hg: rewrite "copystore()" with vfs This patch rewrites "copystore()" with vfs, because succeeding patch requires "lock.lock()" invocation with vfs. This patch uses 'dstbase + "/lock"' instead of "join()" with both elements even on Windows environment but it should be reasonable, because target files given from "store.copyfiles()" already uses "/" as path separator. "util.copyfiles()" between two vfs-s may have to be rewritten in the future.