The original change Id6c58a595 wasn't ready and broke master.
The revert was I5d56a163; this reverts the revert.
Due to a mistake in a condition in LuceneVersionManager#start()
method writer index was never initialized and thus reindexing
of changes was broken. All tests were still passing because the
tests are using SingleVersionModule and not MultiVersionModule.
This reverts commit 6247b52f41.
Change-Id: I5856d3ca2ae6d9549b00aa575abd074ea1ff0bd9
7e638dc280