Move config check until after checkout.
Move config check until after checkout.

There was a silly bug that was checking for YAML config prior to code checkout.
This worked when there was already a cached checkout on disk,
but obviously doesn't respect the config on a fresh build

espdev/readthedocs.org,tddv/readthedocs.org,safwanrahman/readthedocs.org,istresearch/readthedocs.org,davidfischer/readthedocs.org,istresearch/readthedocs.org,stevepiercy/readthedocs.org,rtfd/readthedocs.org,tddv/readthedocs.org,espdev/readthedocs.org,pombredanne/readthedocs.org,tddv/readthedocs.org,espdev/readthedocs.org,pombredanne/readthedocs.org,espdev/readthedocs.org,stevepiercy/readthedocs.org,istresearch/readthedocs.org,safwanrahman/readthedocs.org,istresearch/readthedocs.org,rtfd/readthedocs.org,davidfischer/readthedocs.org,pombredanne/readthedocs.org,safwanrahman/readthedocs.org,safwanrahman/readthedocs.org,davidfischer/readthedocs.org,stevepiercy/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org,stevepiercy/readthedocs.org,espdev/readthedocs.org,davidfischer/readthedocs.org