Upgrade to Lucene 4.10.1 snapshot

[mikemccand]

Upgrades to a snapshot release of 4.10.1, hopefully sidestepping the 1.8.0_20 JVM bug we've been hitting in our builds recently after we upgraded to 4.10.0. This also gives us test coverage of the upcoming Lucene point release...

Closes #7905

[rmuir]

Looks good. I thought the virus scanner would have to be disabled everywhere. Do you have an idea if the two problems are real bugs or just test bugs?

[rjernst]

This looks good. I see you have a 1.4 beta label here. Does that mean you are planning on changing the 1.4 branch to use this as well? I just want to make there is no chance we accidentally release with that? Seems like before release we should remove the repository too.

[mikemccand]

I thought the virus scanner would have to be disabled everywhere.

In fact I had to re-disable it: tests did fail (sometimes).

I see you have a 1.4 beta label here.

Yeah, I think we must upgrade to Lucene 4.10.1 before releasing, else users may hit this nasty 1.8.0_20 JVM bug.

I just want to make there is no chance we accidentally release with that? Seems like before release we should remove the repository too.

I agree: I pushed changes to dev-tools/build_release.py that peek at pom.xml and make sure we are not pointing to the snapshots repository, and that the lucene version is not a snapshot.

[mikemccand]

Do you have an idea if the two problems are real bugs or just test bugs?

One of them (DistributorDirectoryTest) is a test bug: it extends BaseDirectoryTestCase, but in its getDirectory() method it's using MockDirectoryWrappers which BaseDirectoryTestCase does not "support", since it assumes/requires .deleteFile will succeed ... maybe the test should remove the MockDirectoryWrapper when it sees it... not sure.