This commit adds support for the `--ignore-whitespace` option
of the rebase command. This option is simply passed to the
`--am` backend.
Signed-off-by: Pratik Karki <predatoramigo@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>