[PATCH v3 0/2] test-lib.sh: have all tests pass under "-x", remove BASH_XTRACEFD

This re-roll fixes a stupid mistake of mine pointed out by SZEDER[1] (thanks!): I was redirecting to "stderr" across function calls, but some of those changed directories. Now we'll pass around an absolute path from the top-level function.

That bug hid an issue where we'd include the trace output in that stderr log still due to an interpolation of $(pwd), we can just change that to $PWD, which won't have that issue.

1. https://lore.kernel.org/git/20211202192802.GC1991@szeder.dev/

Ævar Arnfjörð Bjarmason (2):
  t1510: remove need for "test_untraceable", retain coverage
  test-lib.sh: remove the now-unused "test_untraceable" facility

 t/README              |  3 --
 t/t1510-repo-setup.sh | 85 +++++++++++++++++++++----------------------
 t/test-lib.sh         | 66 ++++-----------------------------
 3 files changed, 49 insertions(+), 105 deletions(-)

Range-diff against v2:
1:  91402624777 ! 1:  7876202c5b0 t1510: remove need for "test_untraceable", retain coverage
    @@ Commit message
         use of "test_when_finished"), but the pattern enforces better test
         hygiene.
     
    +    The functions it calls might change directories, so we pass an
    +    absolute "$stderr_log_path" around. We also need to change a "$(pwd)"
    +    to "$PWD" in test_repo(), on e.g. "dash" that interpolation will be
    +    traced and part of the "2>>" redirection.
    +
    +    1. https://lore.kernel.org/git/YbMiK1wHzBfYvK2a@coredump.intra.peff.net/
    +
         Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## t/t1510-repo-setup.sh ##
    @@ t/t1510-repo-setup.sh: test_repo () {
      		fi &&
      		rm -f trace &&
     -		GIT_TRACE_SETUP="$(pwd)/trace" git symbolic-ref HEAD >/dev/null &&
    -+		GIT_TRACE_SETUP="$(pwd)/trace" git symbolic-ref HEAD >/dev/null 2>>stderr &&
    ++		GIT_TRACE_SETUP="$PWD/trace" git symbolic-ref HEAD >/dev/null 2>>"$stderr_log_path" &&
      		grep '^setup: ' trace >result &&
      		test_cmp expected result
      	)
    @@ t/t1510-repo-setup.sh: maybe_config () {
      	if test "$value" != unset
      	then
     -		git config --file="$file" "$var" "$value"
    -+		git config --file="$file" "$var" "$value" 2>>stderr
    ++		git config --file="$file" "$var" "$value" 2>>"$stderr_log_path"
      	fi
      }
      
    @@ t/t1510-repo-setup.sh: setup_repo () {
      	sane_unset GIT_DIR GIT_WORK_TREE &&
      
     -	git -c init.defaultBranch=initial init "$name" &&
    -+	git -c init.defaultBranch=initial init "$name" 2>>stderr &&
    ++	git -c init.defaultBranch=initial init "$name" 2>>"$stderr_log_path" &&
      	maybe_config "$name/.git/config" core.worktree "$worktreecfg" &&
      	maybe_config "$name/.git/config" core.bare "$barecfg" &&
      	mkdir -p "$name/sub/sub" &&
    @@ t/t1510-repo-setup.sh: run_wt_tests () {
      #	(git dir) (work tree) (cwd) (prefix)	<-- from subdir
      try_repo () {
      	name=$1 worktreeenv=$2 gitdirenv=$3 &&
    -+	test_when_finished "rm stderr" &&
    ++	stderr_log_path="$PWD/stderr" &&
    ++
    ++	test_when_finished "rm \"$stderr_log_path\"" &&
      	setup_repo "$name" "$4" "$5" "$6" &&
      	shift 6 &&
      	try_case "$name" "$worktreeenv" "$gitdirenv" \
      		"$1" "$2" "$3" "$4" &&
    -+	test_must_be_empty stderr &&
    ++	test_must_be_empty "$stderr_log_path" &&
      	shift 4 &&
      	case "$gitdirenv" in
      	/* | ?:/* | unset) ;;
    @@ t/t1510-repo-setup.sh: try_repo () {
      	try_case "$name/sub" "$worktreeenv" "$gitdirenv" \
     -		"$1" "$2" "$3" "$4"
     +		"$1" "$2" "$3" "$4" &&
    -+	test_must_be_empty stderr
    ++	test_must_be_empty "$stderr_log_path"
      }
      
      # Bit 0 = GIT_WORK_TREE
2:  867d18d14bd = 2:  a7fc794e20d test-lib.sh: remove the now-unused "test_untraceable" facility