servo: Merge #3581 - Pin Cargo to the 2014-10-02 nightly (from Ms2ger:pin-cargo); r=metajack

Relevant to #3580.

Source-Repo: https://github.com/servo/servo
Source-Revision: 8de734f00a9d7598b72acce991410f457169e27a

servo/python/servo/bootstrap_commands.py

@@ -107,7 +107,8 @@ class MachCommands(CommandBase):
         os.mkdir(cargo_dir)
 
         tgz_file = "cargo-nightly-%s.tar.gz" % host_triple()
-        nightly_url = "http://static.rust-lang.org/cargo-dist/%s" % tgz_file
+        # FIXME(#3582): use https.
+        nightly_url = "http://static.rust-lang.org/cargo-dist/2014-10-02/%s" % tgz_file
 
         download("Cargo nightly", nightly_url, tgz_file)