match: use ProgrammingError where appropriate

revlog: raise error.WdirUnsupported from revlog.node() if wdirrev is passed When we try to run, 'hg debugrevspec 'branch(wdir())'', it throws an index error and blows up. Lets raise the WdirUnsupported if wdir() is passed so that we can catch that later.

revset: add support for ancestors(wdir()) This is a part of extending support for wdir() predicate.

revset: add support for using ~ operator on wdir() predicate We catch the WdirUnsupported exception and handles the wdir() case here.