yarn add flat does not behave as expected

[glifchits]

I'm just trying out yarn now, so I do apologize if this is somehow blatantly obvious. In either case I can't see why this happens, after having read the yarn add docs.

I'm trying to install flat (NPM) (Github)

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

This is probably a UX issue or an actual bug.

What is the current behavior?

# testing. this seems to work as expected
$ yarn add react
yarn add v0.17.2
[1/4] 🔍  Resolving packages...
...

# this does not
$ yarn add flat
yarn add v0.17.2
error Missing list of packages to add to your project.
info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.

# what is this doing?
$ yarn add flat flat
yarn add v0.17.2
[1/4] 🔍  Resolving packages...
info Unable to find a suitable version for "debug", please choose one by typing one of the numbers below:
  1) "debug@^2.2.0, debug@^2.1.1, debug@*" which resolved to "2.3.3"
  2) "[email protected], debug@~2.2.0" which resolved to "2.2.0"
  3) "[email protected]" which resolved to "0.7.4"

What is the expected behavior?

$ yarn add flat
yarn add v0.17.2
[1/4] 🔍  Resolving packages...
...

Please mention your node.js, yarn and operating system version.

This happened locally (OSX El Capitan 10.11.6)

# node -v
v7.2.0
# npm -v
3.10.9
# yarn --version
0.17.2

and inside an alpine-node Docker container (FROM mhart/alpine-node:6.9.1)

# node -v
v6.9.1
# npm -v
3.10.8
# yarn --version
0.17.10

[tuures]

workaround: #2220 (comment)

[iredchuk]

Duplicate of #2112

[torifat]

@glifchits Follow #2112 please. Same issue.