* stable-2.15:
NoteDbMigrator: Set checkExisting(false) on PackInserter
ChangeRebuilderImpl: Fail when new NoteDb state is null
PrimaryStorageMigrator: Log individual migrations at debug
Document the deprecation of old change IDs
Update JGit to get PackInserter fix
AbstractChangeNotes: Never open repo when NoteDb is off
MigrateToNoteDb: Only reindex change index
PolyGerrit: Add background-repeat to gr-main-header
Revert "Add privateByDefault config to /config/server/info"
Private state changed event
WIP state changed event
Populate ChangeAttribute with WIP and private status.
Fix invalid json example in POST access endpoint
Add default values in create project dialog and group config
Update JGit to 4.9.2.201712150930-r
gerrit_plugin: Don't add Implementation-Vendor manifest entry
Fix schema_154 migration from version 2.13 and older
Default to writing comments in JSON format
Change-Id: Iee55a0f00ce2430cd400c64491acde3651a0390d
3619a8ffb9