fix empty url condition in add url.
fix empty url condition in add url.

gigablast/open-source-search-engine,gigablast/open-source-search-engine,gigablast/open-source-search-engine,gigablast/open-source-search-engine,gigablast/open-source-search-engine,gigablast/open-source-search-engine,gigablast/open-source-search-engine