[PATCH v4 0/3] difftool dir-diff symlink bug fix and cleanup patches

This patch series fixes a regression in difftool that can lead to data loss. The symlink-file writing in difftool's dir-diff mode has been fixed to no longer write-through to the symlink targets.

Please consider patching older Git versions with the fix from 1/3.

Changes since last time:
- This series has been reordered so that 1/3 is the patch that fixes the bug.
  The subsequent patches are cleanup.
- Patch 1/4 from before, which removed the tmp test repos, has been dropped.
- Patch 1/3 was updated to not remove its tmp test repo.
- Patch 1/3 was updated to consistently use "echo" in its tests.
- Patch 1/3 was updated to fix a "syminks" -> "symlinks" test comment typo.
- Patch 2/3 was reworded to improve the repeated slashes justification.
- Patch 3/3 "add a missing space to the ... comments" is unchanged.

David Aguilar (3):
  difftool: fix symlink-file writing in dir-diff mode
  difftool: use a strbuf to create a tmpdir path without double-slashes
  difftool: add a missing space to the run_dir_diff() comments

 builtin/difftool.c  | 32 ++++++++++---------
 t/t7800-difftool.sh | 75 +++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 91 insertions(+), 16 deletions(-)