repeated Creating/Done historycache messages for the same repository

[vladak]

Running the indexer from scratch I noticed repeated messages within single indexer run:

# grep linux-uek /opengrok-upgrade/log/reindex.log | grep history
15:22:00 INFO: Creating historycache for /ws-local-upgrade/linux-uek-4.1 (GitRepository) without renamed file handling
16:23:06 INFO: Done historycache for /ws-local-upgrade/linux-uek-4.1 (took 1:01:06)
04:53:51 INFO: Creating historycache for /ws-local-upgrade/linux-uek-SPARC (GitRepository) without renamed file handling
06:29:42 INFO: Done historycache for /ws-local-upgrade/linux-uek-SPARC (took 1:35:51)
11:55:42 INFO: Creating historycache for /ws-local-upgrade/linux-uek-4.1 (GitRepository) without renamed file handling
11:56:06 INFO: Done historycache for /ws-local-upgrade/linux-uek-4.1 (took 23.331 seconds)
14:06:29 INFO: Creating historycache for /ws-local-upgrade/linux-uek-SPARC (GitRepository) without renamed file handling
14:07:00 INFO: Done historycache for /ws-local-upgrade/linux-uek-SPARC (took 31.150 seconds)

This is going to skew the indexer statistics for #3245.

Possibly this is related to ensureHistoryCacheExists() called in the 2nd phase of indexing.