Previously a special db table was used to hold domains slated for crawling, but this is deprecated, and instead now each domain has a node_affinity flag that decides its indexing state, where a value of -1 indicates it shouldn't be crawled, a value of 0 means it's slated for crawling by the next index partition to be crawled, and a positive value means it's assigned to an index partition.
The change set also adds a test case validating the modified behavior.
