The bisect log output of skipped commits introduced in f989cac9 "bisect:
Log possibly bad, skipped commits at bisection end" should obtain the range of
skipped commits from

    git rev-list bad --not good-1 good-2

not

    git rev-list bad --not good-1 --not good-2

when the skipped range contains a merge with good points in each parent.
Signed-off-by: NTorstein Hegge <hegge@resisty.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>