Merge branch 'stable-4.7' into stable-4.8

Merge branch 'stable-4.7' into stable-4.8

* stable-4.7:
  Prepare 4.7.9-SNAPSHOT builds
  JGit v4.7.8.201903121755-r
  Prepare 4.5.7-SNAPSHOT builds
  JGit v4.5.6.201903121547-r
  Check for packfile validity and fd before reading
  Move throw of PackInvalidException outside the catch
  Use FileSnapshot to get lastModified on PackFile
  Include size when comparing FileSnapshot
  Do not reuse packfiles when changed on filesystem
  Silence API warnings for new API introduced for fixes

Change-Id: I1136eaa1590b225ceaf16ba7552af0374253a74e
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>