MFB: Fixed bug #47937 (system() calls sapi_flush() regardless of output

buffering)

ext/standard/exec.c

@@ -112,7 +112,9 @@ PHPAPI int php_exec(int type, char *cmd, zval *array, zval *return_value TSRMLS_
 
 			if (type == 1) {
 				PHPWRITE(buf, bufl);
-				sapi_flush(TSRMLS_C);
+				if (OG(ob_nesting_level) < 1) {
+					sapi_flush(TSRMLS_C);
+				}
 			} else if (type == 2) {
 				/* strip trailing whitespaces */
 				l = bufl;