dirstate: add explicit methods for querying directories (API) The set-like object returned by dirstate.dirs may be difficult for other implementations of the dirstate to provide, and is unnecessary as it is only ever used for __contains__. Instead, provide an explicit method for testing for a directory. .. api:: dirstate no longer provides a `dirs()` method. To test for the existence of a directory in the dirstate, use `dirstate.hasdir(dirname)`. Differential Revision: https://phab.mercurial-scm.org/D1345