Disable Quelpa updates if not connected to the Internet

init.org

@@ -63,8 +63,12 @@ Some background is important to understand my keybinding choices -
    :fetcher git
    :url "https://github.com/quelpa/quelpa-use-package.git"))
 (require 'quelpa-use-package)
+;; Don't upgrade Quelpa packages if there's no connectivity.
+;; Courtesy https://emacs.stackexchange.com/a/18515
+(defun my-internet-up-p (host)
+  (= 0 (call-process "ping" nil nil nil "-c" "1" "-W" "1" host)))
 (setq quelpa-checkout-melpa-p nil
-      quelpa-upgrade-p t)
+      quelpa-upgrade-p (my-internet-up-p "github.com"))
 #+END_SRC
 
 * TODO dvorak [60%]