Merge branch 'stable-5.1' into stable-5.2

* stable-5.1:
  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: Id9f957ca8386f6035f4ab34d242cb6fb8c38e012
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>