Merge branch 'ja/perf-use-specified-shell'

Perf tests were run with end-user's shell, but it has been
corrected to use the shell specified by $TEST_SHELL_PATH.

* ja/perf-use-specified-shell:
  t/perf: do not run tests in user's $SHELL

t/perf/perf-lib.sh

@@ -161,7 +161,7 @@ test_run_perf_ () {
 	test_cleanup=:
 	test_export_="test_cleanup"
 	export test_cleanup test_export_
-	"$GTIME" -f "%E %U %S" -o test_time.$i "$SHELL" -c '
+	"$GTIME" -f "%E %U %S" -o test_time.$i "$TEST_SHELL_PATH" -c '
 . '"$TEST_DIRECTORY"/test-lib-functions.sh'
 test_export () {
 	test_export_="$test_export_ $*"