keepalive: send HTTP request headers in a deterministic order An upcoming patch will add low-level testing of the bytes being sent over the wire. As part of developing that test, I discovered that the order of headers in HTTP requests wasn't deterministic. This patch makes the order deterministic to make things easier to test.

revset: properly parse "descend" argument of followlines() We parse "descend" symbol as a Boolean using getboolean (prior extraction by getargsdict already checked that it is a symbol). In tests, check for error cases and vary Boolean values here and there.