In man net, there should be USERSHARE ADD sharename path [comment [acl]] instead of USERSHARE ADD sharename path [comment] [acl]
That's not s4 related as far as I can tell (we have no "net usershare" command).
Fixed in master, thanks. Jeremy.
Pushed to v3-5-test and v3-4-test to get it into the next bug fix releases.