test-lib: use $SHELL_PATH, not $SHELL

The codepath for handling "--tee" ends up relaunching the test
script under a shell, and that one has to be a Bourne.  But we
incorrectly used $SHELL, which could be a non-Bourne (e.g. zsh or
csh); we have the Makefile variable $SHELL_PATH for exactly that,
so use it instead.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/test-lib.sh

@@ -15,22 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see http://www.gnu.org/licenses/ .
 
-# if --tee was passed, write the output not only to the terminal, but
-# additionally to the file test-results/$BASENAME.out, too.
-case "$GIT_TEST_TEE_STARTED, $* " in
-done,*)
-	# do not redirect again
-	;;
-*' --tee '*|*' --va'*)
-	mkdir -p test-results
-	BASE=test-results/$(basename "$0" .sh)
-	(GIT_TEST_TEE_STARTED=done ${SHELL-sh} "$0" "$@" 2>&1;
-	 echo $? > $BASE.exit) | tee $BASE.out
-	test "$(cat $BASE.exit)" = 0
-	exit
-	;;
-esac
-
 # Keep the original TERM for say_color
 ORIGINAL_TERM=$TERM
 
@@ -54,6 +38,22 @@ GIT_BUILD_DIR="$TEST_DIRECTORY"/..
 . "$GIT_BUILD_DIR"/GIT-BUILD-OPTIONS
 export PERL_PATH SHELL_PATH
 
+# if --tee was passed, write the output not only to the terminal, but
+# additionally to the file test-results/$BASENAME.out, too.
+case "$GIT_TEST_TEE_STARTED, $* " in
+done,*)
+	# do not redirect again
+	;;
+*' --tee '*|*' --va'*)
+	mkdir -p test-results
+	BASE=test-results/$(basename "$0" .sh)
+	(GIT_TEST_TEE_STARTED=done ${SHELL_PATH} "$0" "$@" 2>&1;
+	 echo $? > $BASE.exit) | tee $BASE.out
+	test "$(cat $BASE.exit)" = 0
+	exit
+	;;
+esac
+
 # For repeatability, reset the environment to known value.
 LANG=C
 LC_ALL=C