Merge branch 'stable-5.2' into stable-5.3

Merge branch 'stable-5.2' into stable-5.3

* stable-5.2:
  Prepare 5.1.12-SNAPSHOT builds
  JGit v5.1.11.201909031202-r
  Prepare 4.11.10-SNAPSHOT builds
  JGit v4.11.9.201909030838-r
  Bazel: Update bazlets to the latest master revision
  Bazel: Remove FileTreeIteratorWithTimeControl from BUILD file
  BatchRefUpdate: repro racy atomic update, and fix it
  Delete unused FileTreeIteratorWithTimeControl
  Fix RacyGitTests#testRacyGitDetection
  Change RacyGitTests to create a racy git situation in a stable way
  Silence API warnings

Change-Id: I7e88c7c7d202f1e3fb8e143277650aa5fefff439
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>