CDN: trunk Repo update failed - 50 error(s):
CDN: trunk URL couldn't be downloaded: https://raw.githubusercontent.com/CocoaPods/Specs/master/Specs/a/7/5/AFNetworking/0.10.0/AFNetworking.podspec.json, error: execution expired
pod update时报错，折腾了半天发现，把trunk目录删掉，在pod update即可解决。
pod repo remove trunk
pod update
如还不行，可试试更好CDN源
把https://github.com/cocoapods/specs.git换成https://cdn.cocoapods.org/
