Merge branch 'stable-6.4' into stable-6.5

* stable-6.4:
  Remove blank in maven.config
  DirCache: support option index.skipHash

Change-Id: I7f822e8a751516a32afccd180cbf6afb389f3a28

diff --cc org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
Simple merge