Prevent DBException: database or disk is full - Should stop the scan a…

…ndresriancho#5343

Fix unittest

Bump to 1.6.51

Merge branch 'develop' of github.com:andresriancho/w3af into develop

+1

Fixing rfi unittest issues seen at https://circleci.com/gh/andresrian…

…cho/w3af/1108