You can add the --verbose option to your original command line to provide additional information about what SCM commands are being run. Your new command would look something like this:

kwcodereview --url http://server01:8080 --message "Fix for PR55555" --reviewer fbrown,jblack git . --verbose

Adding this option will return more information about why the error occurred and what you can do to fix it. See below for an example.

Example verbose output

server: http://rosenberg:8080/ | test
error: unknown option 'porcelain'
usage: git status [options] [--] <filepattern>...

    -q, --quiet           be quiet
    -v, --verbose         be verbose

Commit message options
    -F, --file <FILE>     read log from file
    --author <AUTHOR>     override author for commit
    -m, --message <MESSAGE>
                          specify commit message
    -c, --reedit-message <COMMIT>
                          reuse and edit message from specified commit
    -C, --reuse-message <COMMIT>
                          reuse message from specified commit
    -s, --signoff         add Signed-off-by:
    -t, --template <FILE>
                          use specified template file
    -e, --edit            force edit of commit

Commit contents options
    -a, --all             commit all changed files
    -i, --include         add specified files to index for commit
    --interactive         interactively add files
    -o, --only            commit only specified files
    -n, --no-verify       bypass pre-commit hook
    --amend               amend previous commit
    -u, --untracked-files[=<mode>]
                          show untracked files, optional modes: all, normal, no.
(Default: all)
    --allow-empty         ok to record an empty change
    --cleanup <default>   how to strip spaces and #comments from message

python: git status --porcelain --untracked-files=no . : exited with non-zero code: 129