This update for varnish fixes the following issues:
Security issue fixed:
CVE-2019-15892: Fixed a potential denial of service by sending crafted HTTP/1 requests (boo#1149382).
Non-security issues fixed:
Updated the package to release 6.2.1.
Added a thread pool watchdog which will restart the worker process if scheduling tasks onto worker threads appears stuck. The new parameter 'thread_pool_watchdog' configures it.
Disabled error for clobbering, which caused bogus error in varnishtest.