Handle errors in varnishncsa formats slightly better
Handle errors in varnishncsa formats slightly better

Print out the rest of the format, changing the error from

  "Unknown format character: {"

to:

  "Unknown format starting at: %{asdf}x"

wikimedia/operations-debs-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,ssm/pkg-varnish,ssm/pkg-varnish,ssm/pkg-varnish