help: present boolean arguments as "--[no-]foo" This should make it much more discoverable (we document it in `hg help flags`, but most users don't think to look there). Note that flags that default to None (and not False) will not get this new presentation. We can change the defaults to False later for flags where it makes sense (probably almost all boolean flags). Differential Revision: https://phab.mercurial-scm.org/D5432