Merge pull request reactjs#194 from emmafallancy/fix-blog-slug-html-creation

Fix the blog slug html creation that leads to improper redirect

Author: bvaughn

gatsby-node.js

@@ -124,11 +124,16 @@ exports.createPages = async ({graphql, boundActionCreators}) => {
             process.exit(1);
           }
 
+          // A leading "/" is required for redirects to work,
+          // But multiple leading "/" will break redirects.
+          // For more context see github.com/reactjs/reactjs.org/pull/194
+          const toPath = slug.startsWith('/') ? slug : `/${slug}`;
+
           redirectToSlugMap[fromPath] = slug;
           createRedirect({
             fromPath: `/${fromPath}`,
             redirectInBrowser: true,
-            toPath: `/${slug}`,
+            toPath,
           });
         });
       }