evolve: make split respect rev args passed without --rev or -r Currently, if one runs `hg split .` or `hg split`, it will fail with an exception. This happens becuase we only expect revision args to be passed as --rev/-r ones and don't treat unnamed args properly or add default values if no args are provided.

test-drop.t
test-inhibit.t
test-simple4server.t
tests/test-simple4server-bundle2.t