Support git's "^" syntax for diffing two commits, for instance via
"--diff HEAD^^^..HEAD".
Signed-off-by: NMichael Ellermann <mpe@ellerman.id.au>
Signed-off-by: NValentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>