If rerere is enabled, no pathnames are given, and mergetool is run
from a subdirectory, mergetool always prints "No files need merging".
Fix the bug.

This regression was introduced in
57937f70a09c12ef484c290865dac4066d207c9c (v2.11.0).

Changes since v3:
  * Update rev-parse docs to use "--" in the --prefix example.
  * Unconditionally run cd_to_toplevel at the beginning to simplify
    the control flow.  Thanks Junio!
  * Test -O<pathname> when there is also a branch named <pathname>.

Richard Hansen (14):
  .mailmap: Use my personal email address as my canonical
  rev-parse doc: use "--" in the --prefix example
  t7610: update branch names to match test number
  t7610: Move setup code to the 'setup' test case.
  t7610: use test_when_finished for cleanup tasks
  t7610: don't rely on state from previous test
  t7610: run 'git reset --hard' after each test to clean up
  t7610: delete some now-unnecessary 'git reset --hard' lines
  t7610: always work on a test-specific branch
  t7610: don't assume the checked-out commit
  t7610: spell 'git reset --hard' consistently
  t7610: add test case for rerere+mergetool+subdir bug
  mergetool: take the "-O" out of $orderfile
  mergetool: fix running in subdir when rerere enabled

 .mailmap                        |   2 +
 Documentation/git-rev-parse.txt |   3 +-
 git-mergetool.sh                |  20 ++-
 t/t7610-mergetool.sh            | 281 ++++++++++++++++++++++++----------------
 4 files changed, 186 insertions(+), 120 deletions(-)

-- 
2.11.0.390.gc69c2f50cf-goog