Upgrade bazlets to latest stable-2.14

- download_file.py: Synchronize curl options with gerrit core

Change-Id: Ic57b35e489a4a95a2e8a259741c79d38ba657047

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 2f73ae8..f581a65 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "e045706f9e7b4aa883b14b7779c1c576f455220a",
+    commit = "b750c0adec6deebb1063219787a97fab1d32724b",
     #local_path = "/home/<user>/projects/bazlets",
 )