Jason Tedor 7ce06aeb8c Fix date format in warning headers
This commit fixes the date format in warning headers. There is some
confusion around whether or not RFC 1123 requires two-digit
days. However, the warning header specification very clearly relies on a
format that requires two-digit days. This commit removes the usage of
RFC 1123 date/time format from Java 8, which allows for one-digit days,
in favor of a format that forces two-digit days (it's otherwise
identical to RFC 1123 format, it is just fixed width).

Relates #23418
2017-02-28 20:28:07 -05:00
..