help: enable listing of a subset of the command list
Instead of giving the "command %s is ambiguous" error message
with a bare list of possible command, display help list
for all commands starting with the given string.
adding a
updating working directory
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b
pushing to ../a
abort: could not lock repository ../a: Permission denied