More HgExtractor improvements
Delete some orphaned code, and add a housekeeping callback which (after every 1000 processed commits) shuts down the Hg command server and starts a new one, to work around memory leaks in Hg.
Delete some orphaned code, and add a housekeeping callback which (after every 1000 processed commits) shuts down the Hg command server and starts a new one, to work around memory leaks in Hg.