Check asprintf() return value.

plugins/python/regress/testhelpers.c

@@ -255,13 +255,17 @@ int
 mock_python_datetime_now(const char *plugin_name, const char *date_str)
 {
     char *cmd = NULL;
-    asprintf(&cmd, "import %s\n"                      // the plugin has its own submodule
+    int len;
+    len = asprintf(&cmd,
+                   "import %s\n"                      // the plugin has its own submodule
                    "from datetime import datetime\n"  // store the real datetime
                    "import time\n"
                    "from unittest.mock import Mock\n"
                    "%s.datetime = Mock()\n"           // replace plugin's datetime
                    "%s.datetime.now = lambda: datetime.strptime('%s', '%%Y-%%m-%%dT%%H:%%M:%%S')\n",
              plugin_name, plugin_name, plugin_name, date_str);
+    if (len == -1)
+	return false;
     VERIFY_PTR_NE(cmd, NULL);
     VERIFY_INT(PyRun_SimpleString(cmd), 0);
     free(cmd);