Retry icon download

Summary:
In public CI (only?), asset downloads sometimes fail with a spurious 404.
We already have retrying in place, but it will obviously not do that on a 500.

Reviewed By: nikoant

Differential Revision: D28744817

fbshipit-source-id: b6a185d8e9db45e02c6427233a0171b00c552751

desktop/scripts/build-release.ts

@@ -317,7 +317,13 @@ function downloadIcons(buildFolder: string) {
   return Promise.all(
     iconURLs.map(({name, size, density}) => {
       const url = getIconURL(name, size, density);
-      return fetch(url, {})
+      return fetch(url, {
+        retryOptions: {
+          // Be default, only 5xx are retried but we're getting the odd 404
+          // which goes away on a retry for some reason.
+          retryOnHttpResponse: (res) => res.status >= 400,
+        },
+      })
         .then((res) => {
           if (res.status !== 200) {
             throw new Error(