Yarn hangs forever when missing write access

[androa]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
If yarn need to write in a read-only directory, it hangs forever.

If the current behavior is a bug, please provide the steps to reproduce.

mkdir -m 500 bar && cd bar
yarn init -y

Then yarn says it successfully has written package.json, but just hangs forever.

What is the expected behavior?
For yarn to report the missing write access and exit.

Please mention your node.js, yarn and operating system version.
node v6.9.1; yarn from source; official node docker image.

[androa]

Seems to have been solved by #1592 and this can be closed.