Eliminate a NULL pointer issue with empty (apart from comments and whitespace) testfiles.
Eliminate a NULL pointer issue with empty (apart from comments and
whitespace) testfiles.

Spotted by:	Coverity

gquintard/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache