test-lib: replace chainlint.sed with chainlint.pl

By automatically invoking chainlint.sed upon each test it runs,
`test_run_` in test-lib.sh ensures that broken &&-chains will be
detected early as tests are modified or new are tests created since it
is typical to run a test script manually (i.e. `./t1234-test-script.sh`)
during test development. Now that the implementation of chainlint.pl is
complete, modify test-lib.sh to invoke it automatically instead of
chainlint.sed each time a test script is run.

This change reduces the number of "linter" invocations from 26800+ (once
per test run) down to 1050+ (once per test script), however, a
subsequent change will drop the number of invocations to 1 per `make
test`, thus fully realizing the benefit of the new linter.

Note that the "magic exit code 117" &&-chain checker added by bb79af9d09
(t/test-lib: introduce --chain-lint option, 2015-03-20) which is built
into t/test-lib.sh is retained since it has near zero-cost and
(theoretically) may catch a broken &&-chain not caught by chainlint.pl.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/test-lib.sh b/t/test-lib.sh
index dc0d059..a65df2f 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1091,8 +1091,7 @@
 		trace=
 		# 117 is magic because it is unlikely to match the exit
 		# code of other programs
-		if $(printf '%s\n' "$1" | sed -f "$GIT_BUILD_DIR/t/chainlint.sed" | grep -q '?![A-Z][A-Z]*?!') ||
-			test "OK-117" != "$(test_eval_ "(exit 117) && $1${LF}${LF}echo OK-\$?" 3>&1)"
+		if test "OK-117" != "$(test_eval_ "(exit 117) && $1${LF}${LF}echo OK-\$?" 3>&1)"
 		then
 			BUG "broken &&-chain or run-away HERE-DOC: $1"
 		fi
@@ -1588,6 +1587,12 @@
 	BAIL_OUT_ENV_NEEDS_SANITIZE_LEAK "GIT_TEST_SANITIZE_LEAK_LOG=true"
 fi
 
+if test "${GIT_TEST_CHAIN_LINT:-1}" != 0
+then
+	"$PERL_PATH" "$TEST_DIRECTORY/chainlint.pl" "$0" ||
+		BUG "lint error (see '?!...!? annotations above)"
+fi
+
 # Last-minute variable setup
 USER_HOME="$HOME"
 HOME="$TRASH_DIRECTORY"