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 v1:
  * Patch 2/4 was reworked to improve the commit message, improve test
    case independence even further, and use 'test_when_finished "git
    reset --hard"' instead of a plain 'git reset --hard'.

Richard Hansen (4):
  t7610: update branch names to match test number
  t7610: make tests more independent and debuggable
  t7610: add test case for rerere+mergetool+subdir bug
  mergetool: fix running in subdir when rerere enabled

 git-mergetool.sh     |   1 +
 t/t7610-mergetool.sh | 251 ++++++++++++++++++++++++++++++---------------------
 2 files changed, 147 insertions(+), 105 deletions(-)

-- 
2.11.0.390.gc69c2f50cf-goog