gutenberg/gutenberg — pull request #499 by abhinavc (2013-11-01 07:35:18+00:00)
Title: [vault.mk]: preview.tex should be dependent on question.tex

Also, create_tex_from_blueprint does not delete preview.tex.
Which means, that even when question.tex changes, it does not
trigger re-make of preview.tex

Delete the old preview.tex as part of the recipe