Don't overwrite unwind exception

Author: nikic

Zend/zend_exceptions.c

@@ -175,6 +175,12 @@ ZEND_API ZEND_COLD void zend_throw_exception_internal(zend_object *exception) /*
 
 	if (exception != NULL) {
 		zend_object *previous = EG(exception);
+		if (previous && (zend_is_unwind_exit(previous) || zend_is_graceful_exit(previous))) {
+			/* Don't replace unwinding exception with different exception. */
+			OBJ_RELEASE(exception);
+			return;
+		}
+
 		zend_exception_set_previous(exception, EG(exception));
 		EG(exception) = exception;
 		if (previous) {