Merge branch 'stable-5.3'

* stable-5.3:
  Prepare 5.3.0-SNAPSHOT builds
  JGit v5.3.0.201903061415-rc1
  Fix error log message in ObjectDirectory.handlePackError()
  Properly format pack checksums in PackFile.idx()
  Cancel gc if thread was interrupted
  PackFile: report correct message for checksum mismatch
  ObjectDirectory: Clean up logging
  Bazel: Stop using native.git_repository
  ObjectDirectory: extra logging on packfile exceptions

Change-Id: I8c7dfd5141be0d27547d65f19054f9a1665b55fb