yarn install v1.6.0
[1/4] 馃攳 Resolving packages...
[2/4] 馃殮 Fetching packages...
error An unexpected error occurred: "https://registry.yarnpkg.com/jest/-/jest-23.0.0-alpha.0.tgz: Request failed \"404 Not Found\"".
info If you think this is a bug, please open a bug report with the information provided in "/home/gagan/vcs/fork/spring-keyframes/yarn-error.log".
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.

Looks like an issue with yarn registry, but there's plenty of other alphas and betas for this release that work:

If anyone still facing the same problem run the following commands:
yarn config set registry https://registry.npmjs.org
rm yarn.lock
yarn install
Most helpful comment
If anyone still facing the same problem run the following commands: