Performance Improvements

581723 Support the new option index.skipHash which was introduced in git 2.40. 
    If it is set to true skip computing the git index checksum. This
    accelerates Git commands that manipulate the index, such as git add, git
    commit, or git status.
Allow to perform PackedBatchRefUpdate without locking loose refs
Shortcut during git fetch for avoiding looping through all local refs
Allow the exclusions of refs prefixes from bitmap index generation
581267 PackWriterBitmapPreparer: do not include annotated tags in bitmap index
Speedup GC listing objects referenced from reflogs
580310 Add option to allow using JDK's SHA1 implementation
579805 Do not create reflog for remote tracking branches during clone
UploadPack: do not check reachability of visible SHA1s at the tips of an advertised ref

Bug Fixes

582044 Revert "RefDirectory: Throw exception if CAS of packed ref list fails"
Prevent infinite loop rescanning the pack list on PackMismatchException
GC: Close File.lines stream
If tryLock fails to get the lock another gc has it
Don't swallow IOException in GC.PidLock#lock
Check if FileLock is valid before using or releasing it
Acquire file lock "gc.pid" before running gc
Add pack options to preserve and prune old pack files
FetchCommand: fix fetchSubmodules to work on a Ref to a blob
BatchingProgressMonitor: avoid int overflow when computing percentage
580953 Ignore IllegalStateException if JVM is already shutting down
579670 UploadPack: don't prematurely terminate timer in case of error
577018 Add missing package import javax.management to org.eclipse.jgit