[rake] Make `rake bootstrap` work when Bundler tries to exit.
[rake] Make `rake bootstrap` work when Bundler tries to exit.

billinghamj/trunk.cocoapods.org,CocoaPods/trunk.cocoapods.org,k0nserv/trunk.cocoapods.org,Shawn-WangDapeng/trunk.cocoapods.org,Shawn-WangDapeng/trunk.cocoapods.org,CocoaPods/trunk.cocoapods.org,k0nserv/trunk.cocoapods.org,k0nserv/trunk.cocoapods.org,billinghamj/trunk.cocoapods.org