Merge branch 'dl/checkout-p-merge-base'

"git checkout -p A...B [-- <path>]" did not work, even though the
same command without "-p" correctly used the merge-base between
commits A and B.

* dl/checkout-p-merge-base:
  t2016: add a NEEDSWORK about the PERL prerequisite
  add-patch: add NEEDSWORK about comparing commits
  Doc: document "A...B" form for <tree-ish> in checkout and switch
  builtin/checkout: fix `git checkout -p HEAD...` bug

diff --cc Documentation/git-checkout.txt
Simple merge

diff --cc add-patch.c
Simple merge

diff --cc builtin/checkout.c
Simple merge

diff --cc git-add--interactive.perl
Simple merge