engine: 'if not, else' -> 'if, else' I personally feel that ``` if x: pass else: pass ``` is easier to read and edit than ``` if not x: pass else: pass ``` Next patches will add one more if-else clause. Differential Revision: https://phab.mercurial-scm.org/D9931

debugcommands: s/stdin/stdout in debugnodemap help Differential Revision: https://phab.mercurial-scm.org/D9930

errors: use InputError in uncommit extension Differential Revision: https://phab.mercurial-scm.org/D9911