better unsupported error message

pickfire · kinnison · web-flow · commit 11c79727210d · 2020-07-27T16:00:57.000+08:00
Co-authored-by: Daniel Silverstone &lt;dsilvers@digital-scurf.org&gt;
diff --git a/rustup-init.sh b/rustup-init.sh
@@ -418,7 +418,7 @@ downloader() {
         if [ -n "$_err" ]; then
             echo "$_err" >&2
             if echo "$_err" | grep -q 404$; then
-                err "unsupported platform $3"
+                err "installer for platform '$3' not found, this may be unsupported"
             fi
         fi
         return $_status
