title: CocoaPods error: RPC failed; curl 18 transfer closed with outstanding read data remaining
body: <p>When I tried to import Realm with CocoaPods like this:
  <code>
  pod install --verbose --no-repo-update
  </code>
  then error happened:
  <code>
  error: RPC failed; curl 18 transfer closed with outstanding read data remaining
       fatal: The remote end hung up unexpectedly
       fatal: early EOF
       fatal: index-pack failed
       fatal: clone of 'https://github.com/ColinH/PEGTL' into submodule path '/private/var/folders/51/tzbm7yqs3bsck5vxz3xj5pkc0000gn/T/d20160925-2957-1pu1dou/Realm/ObjectStore/external/pegtl' failed
  </code>
  why?</p>