conda_build/source.py: Simplify `if` statement to avoid redundancy.
conda_build/source.py: Simplify `if` statement to avoid redundancy.

dan-blanchard/conda-build,rmcgibbo/conda-build,ilastik/conda-build,mwcraig/conda-build,sandhujasmine/conda-build,rmcgibbo/conda-build,ilastik/conda-build,dan-blanchard/conda-build,rmcgibbo/conda-build,ilastik/conda-build,sandhujasmine/conda-build,sandhujasmine/conda-build,mwcraig/conda-build,dan-blanchard/conda-build,mwcraig/conda-build