Merge branch 'stable-6.2' into stable-6.3

Merge branch 'stable-6.2' into stable-6.3

* stable-6.2:
  Shortcut during git fetch for avoiding looping through all local refs
  FetchCommand: fix fetchSubmodules to work on a Ref to a blob
  Silence API warnings introduced by I466dcde6
  Allow the exclusions of refs prefixes from bitmap
  PackWriterBitmapPreparer: do not include annotated tags in bitmap
  BatchingProgressMonitor: avoid int overflow when computing percentage
  Speedup GC listing objects referenced from reflogs
  FileSnapshotTest: Add more MISSING_FILE coverage

Change-Id: I2ff386d9a096277360e6c7bd5535b49984620fb3