blockToDesiredReplication map[blockdigest.DigestWithSize]int,
underReplicated BlockSet) (m map[Locator]PullServers) {
m = map[Locator]PullServers{}
blockToDesiredReplication map[blockdigest.DigestWithSize]int,
underReplicated BlockSet) (m map[Locator]PullServers) {
m = map[Locator]PullServers{}