ESI onerror="abort" handling for OC_F_FAILED

[nigoroll]

noticed en passant : We should probably also abort for this case

varnish-cache/bin/varnishd/cache/cache_esi_deliver.c

Lines 900 to 904 in 9036119

	if (req->objcore->flags & OC_F_FAILED) {
	/* No way of signalling errors in the middle of
	the ESI body. Omit this ESI fragment. */
	return;
	}

[bsdphk]

Noted as part of discussion: ESI spec says

»If an ESI Processor can fetch neither the src nor the alt, it returns a HTTP status code greater than 400 with an error message, unless the onerror attribute is present.«