* stable-4.3:
Scan loose ref before packed in case gc about to remove the loose
Fix possible NPEs when reporting transport errors
Fix calling of clean/smudge filters from Checkout,MergeCommands
Fix ApplyCommand when result of patch is an empty file
Change-Id: I0dc76b7a8c87ce8e0386a1b9e0fa92a3aa62abf7 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>