RFC 7538[1] added HTTP response code 308, signifying a permanent
redirect that, contrary to the older 301, does not allow changing
the request method from POST to GET.
[1] https://tools.ietf.org/html/rfc7538
Bug: 560936
Change-Id: Ib65f3a3ed75db51d74d1fe81d4abe6fe92b0ca12
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>