revset: make default kind of pattern for "contains()" rooted at cwd Before this patch, default kind of pattern for revset predicate "contains()" is treated as the exact file path rooted at the root of the repository. This decreases usability, because: - all other predicates taking pattern argument (also "filelog()") treat such pattern as the path rooted at the current working directory - "contains()" doesn't describe this difference in its help - this difference may confuse users for example, this prevents revset aliases from sharing same argument between "contains()" and other predicates This patch makes default kind of pattern for revset predicate "contains()" be rooted at the current working directory. This patch uses "pathutil.canonpath()" instead of creating "match" object for efficiency.