Consider use of p4 shelve / p4 unshelve for pre commit reviews

The latest version of perforce adds two new commands p4 shelve and p4 unshelve.

#208746 (Bug #15043) **
Two new commands, 'p4 shelve' and 'p4 unshelve', enable
developers to store and retrieve files on the Perforce server
without submitting them. These commands make multi-tasking,
code sharing, testing and review much easier and more practical.
Users gain access to shelved files and their content through
'describe', 'changes' 'fstat', 'diff', 'diff2', 'files' and
'print'. See 'p4 help shelve/unshelve' for more information.

So it allows you to store a potential changeset on the server without doing a p4 submit. Might be a nice way to handle pre-commit reviews.