* JGit v5.3.8.202011260953-r

* SimpleMergeTest: Clean up code style

* Fix ProtectedMembersInFinalClass warning flagged by error prone

* Scan through all merged reftables for max/min update indices

* Update Orbit to I20200126235943 and org.junit to 4.13.0.v20200126-2018
* Fix SshSessionFactory#setInstance to use service loader

* 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

* Merge branch 'stable-5.1' into stable-5.2

* JGit v5.4.0.201906120450-r

* Fix FileSnapshotTest.testNewFileNoWait() to match its javadoc
* ObjectDirectory: fix closing of obsolete packs

* pgm: Fix missing braces in Push.run()
* pgm: Handle exceptions in Push command
* pgm: Fix missing braces in MergeBase.run()
* pgm: Handle IOException in MergeBase command
* pgm: Fix missing braces in Merge command
* pgm: Handle exceptions in Merge command
* pgm: Fix missing braces in LsTree.run()
* pgm: Handle exceptions in LsTree command
* pgm: Fix missing braces in LsRemote.run()
* pgm: Handle exceptions in LsRemote command
* pgm: Handle exceptions in LsFiles command
* pgm: Fix missing braces in Log.run()
* pgm: Handle exceptions in Log command
* pgm: Handle exceptions in Init command
* pgm: Handle IOException in IndexPack command
* pgm: Fix missing braces in Fetch.run()
* pgm: Handle IOException in Fetch command
* pgm: Handle GitAPIException in Gc command
* pgm: Fix missing braces in DiffTree.run()
* pgm: Handle exceptions in DiffTree command

* Upgrade spotbugs-maven-plugin to 3.1.2

* Fix version of slf4j in manifest files

* Upgrade maven-javadoc-plugin to 3.0.0
* Upgrade maven-surefire{-report}-plugin to 2.20.1

* CloneCommand: Refactor listing of files in deleteChildren

* DfsBlockCache#creditSpace: release clockLock in finally block
* ArchiveTest: Check result of BufferedInputStream#skip
* FS_POSIX: Fix boxing/unboxing of Boolean
* Use constants from StandardCharsets instead of hard-coded strings
* LfsServerText: Fix formatting of invalidPathInfo message
* InvalidLongObjectIdException: Fix formatting of message
* Move repeated LFS Gson handling to common class
* DownloadTest: Use ExpectedException instead of try..catch..fail

* ReftableCompactor should accept 0 for minUpdateIndex

* FileMode: Remove unnecessary @SuppressWarnings("synthetic-access")

* reftable: reserve standard PackExt
* reftable: resolve symbolic references
* reftable: support threshold based compaction
* reftable: compact merged tables
* reftable: merge-join reftables
* reftable: lookup by ObjectId unit tests
* reftable: reflog unit tests
* reftable: namespace unit tests
* reftable: bulk operation unit tests
* reftable: basic functionality unit tests
* reftable: debug tools
* reftable: scan and lookup reftable files
* reftable: create and write reftable files
* reftable: file format documentation

* Add LfsPointerFilter TreeFilter

* Configure Maven to run tests concurrently by default

* CleanFilter: use atomic move to move temporary file to media file

* Add testCleanDirsWithSubmodule test to CleanCommandTest

* Add ignoreRemoteFailures option to RepoCommand

* Remove BitmapRevFilter.getCountOfLoadedCommits
* Make BitmapBuilder.getBitmapIndex public
* Deprecate BitmapBuilder.add and introduce simpler addObject method
* Add @Override annotations to BitmapIndexImpl
* Rely on bitmap RevFilter to filter walk during bitmap selection
* Use 'reused' bitmap to filter walk during bitmap selection
* Rely on bitmap RevFilter to filter tip commit setup walk
* Use 'reused' bitmap to filter tip commit setup walk
* Include ancestors of reused bitmap commits in reuse bitmap again

* Add bitmap index misses to PackWriter.Statistics

* Replace deprecated release() methods by close()
* Use AutoClosable to close resources in bundle org.eclipse.jgit

* Add "--long" option to JGit describe

* Prepare post 3.4.0 RC1 builds

* Detects background authentication and force use of jgit authentication

* Use RawParseUtils.prevLF in RebaseCommand
* Support aborting non-interactive rebase started from C Git

* Fix ResolveMerger issue with submodule conflict

* Fix constructor for SafeBufferedOutputStream

* DHT: Change DhtReadher caches to be dynamic by workload
* DHT: Use a proper HashMap for RecentChunk lookups
* DHT: Always have at least one recent chunk in DhtReader
* DHT: Fix NPE during prefetch
* DHT: Drop leading hash digits from row keys