OK: i think the core/src/test-files/solr/data svn:ignore is nuked in trunk and branch_3x.
As i said before its still not perfect, and I put comments in NoCacheHeaderTest indicating its broken,
because if two different tests try to write to this sync'ed build/test-files directory at the same time,
then it will cause strange fails.
But its an improvement in the sense that we don't need the special ant clean, we don't dirty up the
source tree, and sync task (called by compile-test) should nuke any leftover indexes created from
the previous run.