commit: option equivalent to git's -e/--edit to force edit of -m/-F option

git permits forcing the edit of a commit message presented on the command line by -m or -F:

       -e, --edit
           The message taken from file with -F, command line with -m, and from
           file with -C are usually used as the commit log message unmodified.
           This option lets you further edit the message taken from these
           sources.

bzr should have a similar option.