cherry-pick: enforce `--keep-redundant-commits` incompatibility
When `--keep-redundant-commits` was added in
b27cfb0d8d
(git-cherry-pick: Add keep-redundant-commits option, 2012-04-20), it was
not marked as incompatible with the various operations needed to
continue or exit a cherry-pick (`--continue`, `--skip`, `--abort`, and
`--quit`).
Enforce this incompatibility via `verify_opt_compatible` like we do for
the other various options.
Signed-off-by: Brian Lyles <brianmlyles@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>