Fail if core=tarantool default server failed

Currently we stop default server in worker run loop only before the
next test start. So the previous test does not account whether the
Tarantool executing the test exits successfully or not. Thus we
do not fail on memory leaks for example.

Let's stop the server and account its exit status in test.

Closes tarantool#416

lib/test.py

@@ -218,6 +218,7 @@ def run(self, server):
         sys.stdout.flush()
 
         is_tap = False
+        is_crashed = False
         if not self.skip:
             if not os.path.exists(self.tmp_result):
                 self.is_executed_ok = False
@@ -233,6 +234,9 @@ def run(self, server):
                 is_tap, is_ok, is_skip = self.check_tap_output()
                 self.is_equal_result = is_ok
                 self.skip = is_skip
+
+            server.stop(silent=True)
+            is_crashed = server.current_test.is_crash_reported
         else:
             self.is_equal_result = 1
 
@@ -250,7 +254,8 @@ def run(self, server):
                 os.remove(self.tmp_result)
         elif (self.is_executed_ok and
               self.is_equal_result and
-              self.is_valgrind_clean):
+              self.is_valgrind_clean and
+              not is_crashed):
             short_status = 'pass'
             color_stdout("[ pass ]\n", schema='test_pass')
             if os.path.exists(self.tmp_result):