--- httpd-2.4.29.orig/server/util.c	2017-10-10 20:25:14.000000000 +0900
+++ httpd-2.4.29.orig/server/util.c	2017-11-25 15:18:25.710606884 +0900
@@ -3155,6 +3155,17 @@ 
     buf[k] = '\0'; 
     apr_file_close(fp);
 
+    {   /* http://dev.ariel-networks.com/apr/apr-tutorial/html/apr-tutorial-14.html */
+        int st;
+        apr_exit_why_e why;
+        apr_status_t rv = apr_proc_wait(proc, &st, &why, APR_WAIT);
+        if (!APR_STATUS_IS_CHILD_DONE(rv)) {
+            ap_log_perror(APLOG_MARK, APLOG_WARNING, 0, NULL, APLOGNO(00599)
+                          "%s: apr_proc_wait() child not done",
+                          cmd);
+        }
+    }
+
     return apr_pstrndup(p, buf, k);
 }