Allow `rad patch edit` to take a `--revision` option which will edit
the description of the specified revision, rather than the root
revision.
If the flag is not specified, then the original behaviour of editing
the root revision's title and description is used.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
Fintan Halpenny