proxy.config.http.cache.required_headers value 1 does not allow caching of items with only Cache-Control: max-age

the records.config variable proxy.config.http.cache.required_headers has three options:

1. 0 - No required headers to make document cachable
2. 1 - at least "Last-Modified:" header required
3. 2 - explicit lifetime required, "Expires:" or "Cache-Control:"

The options are ordered in least restrictive to most restrictive. However, choosing option 1 does not allow YTS to cache objects with CC: max-age, whereas option 2 allows it.