Silently ignore invalid set ' ' and invalid help help commands. This is the same fix applied by NetBSD in hg commit 1019940:4f248823eaff. PR: 265097 Reported by: Simon Josefsson <simon@josefsson.org> Obtained from: NetBSD hg commit 1019940:4f248823eaff NetBSD PR/56918 MFC after: 1 week