[PATCH v2 0/5] commit-graph: test cleanup and modernization

Here is a reroll of my series to address a few style nitpicks in the commit-graph tests.

Much is the same from the previous round, except for:

  - quotes >"$DIR/expect" to ensure that we work on all shells>
  - adds a NOTE above graph_git_behavior to indicate that its second
    argument cannot contain any character in $IFS.
  - rebased on top of the current tip of 'master'.

As usual, a range-diff is available below. Thanks in advance for your review!

Taylor Blau (5):
  t/lib-commit-graph.sh: allow `graph_read_expect()` in sub-directories
  t/lib-commit-graph.sh: avoid directory change in
    `graph_git_behavior()`
  t5318: avoid top-level directory changes
  t5328: avoid top-level directory changes
  t/lib-commit-graph.sh: avoid sub-shell in `graph_git_behavior()`

 t/lib-commit-graph.sh              |  34 ++-
 t/t5318-commit-graph.sh            | 378 +++++++++++++----------------
 t/t5328-commit-graph-64bit-time.sh |  54 ++---
 3 files changed, 224 insertions(+), 242 deletions(-)

Range-diff against v1:
1:  08482212630 ! 1:  c81a059c181 t/lib-commit-graph.sh: allow `graph_read_expect()` in sub-directories
    @@ t/lib-commit-graph.sh: graph_read_expect() {
      		OPTIONS=" read_generation_data"
      	fi
     -	cat >expect <<- EOF
    -+	cat >$DIR/expect <<- EOF
    ++	cat >"$DIR/expect" <<-EOF
      	header: 43475048 1 $(test_oid oid_version) $NUM_CHUNKS 0
      	num_commits: $1
      	chunks: oid_fanout oid_lookup commit_metadata$OPTIONAL
2:  715a160903b ! 2:  115df6fe226 t/lib-commit-graph.sh: avoid directory change in `graph_git_behavior()`
    @@ Commit message
         Signed-off-by: Taylor Blau <me@ttaylorr.com>
     
      ## t/lib-commit-graph.sh ##
    -@@ t/lib-commit-graph.sh: graph_git_behavior() {
    +@@ t/lib-commit-graph.sh: graph_git_two_modes() {
    + 	test_cmp expect output
    + }
    + 
    ++# graph_git_behavior <name> <directory> <branch> <compare>
    ++#
    ++# Ensures that a handful of traversal operations produce the same
    ++# results with and without the commit-graph in use.
    ++#
    ++# NOTE: it is a bug to call this function with <directory> containing
    ++# any characters in $IFS.
    + graph_git_behavior() {
    + 	MSG=$1
    + 	DIR=$2
      	BRANCH=$3
      	COMPARE=$4
      	test_expect_success "check normal git operations: $MSG" '
3:  451ec003be8 = 3:  12ce967bafe t5318: avoid top-level directory changes
4:  ba550987055 = 4:  79b3444660f t5328: avoid top-level directory changes
5:  c3432f27b94 = 5:  887006eab46 t/lib-commit-graph.sh: avoid sub-shell in `graph_git_behavior()`