* stable-5.5: Prepare 5.1.17-SNAPSHOT builds JGit v5.1.16.202106041830-r BatchRefUpdate: Skip saving conflicting ref names and prefixes in memory BatchRefUpdateTest: Accurately assert RefsChangedEvent(s) fired Optimize RefDirectory.isNameConflicting() Update bazlets and bazel version Change-Id: I504483a4dc979c5e7af18bad45dc18675e32afd2