tests: add test for https://github.com/systemd/systemd/issues/2637

+ perl -e 'exit(!(qq{0} eq qq{\x25U}))'
exec-spec-interpolation.service: Main process exited, code=exited, status=1/FAILURE
exec-spec-interpolation.service: Unit entered failed state.
exec-spec-interpolation.service: Failed with result 'exit-code'.
        PID: 11270
        Start Timestamp: Wed 2016-02-17 22:21:31 UTC
        Exit Timestamp: Wed 2016-02-17 22:21:31 UTC
        Exit Code: exited
        Exit Status: 1
Assertion 'service->main_exec_status.status == status_expected' failed at src/test/test-execute.c:65, function check(). Aborting.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/test/test-execute.c b/src/test/test-execute.c
index 92857cb5e2..d021be4671 100644
--- a/src/test/test-execute.c
+++ b/src/test/test-execute.c
@@ -263,6 +263,10 @@ static void test_exec_ioschedulingclass(Manager *m) {
         test(m, "exec-ioschedulingclass-best-effort.service", 0, CLD_EXITED);
 }
 
+static void test_exec_spec_interpolation(Manager *m) {
+        test(m, "exec-spec-interpolation.service", 0, CLD_EXITED);
+}
+
 int main(int argc, char *argv[]) {
         test_function_t tests[] = {
                 test_exec_workingdirectory,
@@ -284,6 +288,7 @@ int main(int argc, char *argv[]) {
                 test_exec_capabilityambientset,
                 test_exec_oomscoreadjust,
                 test_exec_ioschedulingclass,
+                test_exec_spec_interpolation,
                 NULL,
         };
         test_function_t *test = NULL;