[PATCH 0/4] Fix issues and a regression noted by valgrind

I spotted these when testing v2.36.0, but waited until after the release since there's no v2.36.0 regressions here.

The scariest issue here by far is one I caused and am now fixing in 4/4. As noted I don't think it had any real practical fallout, but we should obviously fix it sooner than later.

I think the 3/4 issue is likewise just a bit scary, but I haven't analyzed it as much. In that case we'd pass uninitialized memory to a syscall.

It's clear that the --valgrind mode for the test suite is useful, but it's sooo sloooow (it takes around a full day to complete, and for me the full tests otherwise run in ~2 minutes). I'll try to run it in the background with some regularity going forward anyway.

Aside: I do see that there's occasionaly FreeBSD runs in the "main"
git/git CI. How are those hooked up? Running it in GitHub CI would
take approximately forever (I think it would run into a hard timeout),
but if we can hook up a CI runner on some dedicated hardware.

Ævar Arnfjörð Bjarmason (4):
  tests: make RUNTIME_PREFIX compatible with --valgrind
  log test: skip a failing mkstemp() test under valgrind
  commit-graph.c: don't assume that stat() succeeds
  object-file: fix a unpack_loose_header() regression in 3b6a8db3b03

 commit-graph.c        |  6 ++++--
 object-file.c         |  8 ++++++--
 t/t0060-path-utils.sh |  4 ++--
 t/t1006-cat-file.sh   | 10 ++++++++--
 t/t1450-fsck.sh       | 13 +++++++++++--
 t/t4202-log.sh        | 11 +++++++----
 t/test-lib.sh         |  1 +
 7 files changed, 39 insertions(+), 14 deletions(-)