* changes:
ReceiveCommits: document CreateRequest and ReplaceRequest
Change: document the Change.Key type
ReceiveCommits: make inner class ChangeLookup static
ReceiveCommits: drop warnings about unchanged tree for autoClose
ReceiveCommits: split validateNewPatchSetCommit into multiple functions
ReceiveCommits: drop superfluous check for writable project
ReceiveCommits: remove dead code in validateNewPatchSetCommit.
ReceiveCommits: use local scope for progress counters