Previously, when handling an object POST, if the proxy got a 202 and
two connection timeouts from the 3 primary backend object servers, it
then went to two handoffs which return 404. The proxy would consider
this to be a quorum of 404s and return the client a 404 response. This
is alarming for the client.
With this patch, the proxy will only treat a 404 response from a
handoff as authoritative if it has an x-backend-timestamp header
(i.e. there's a tombstone on the handoff). POST responses never have
an x-backend-timestamp header so in the scenario described above the
proxy will return a 503.
The Related-Change previously made a similar fix such that 404s from
handoffs are already non-authoritative for object GETs and HEADs
unless they have an x-backend-timestamp header.
Related-Change: Ia832e9bab13167948f01bc50aa8a61974ce189fb
Cloeses-Bug: #2077743
Change-Id: I96f28ab0b2b5f9374c399e8905ee240e7b093f8b
d0f6a0ce56