[travis ruby-2.1-head] Apparently ruby 2.1-head isn't a thing.

Using worker: worker-linux-10-1.bb.travis-ci.org:travis-linux-10
git.1
$ git clone --depth=50 --branch=master git://github.com/tsnow/shout.git tsnow/shout
Cloning into 'tsnow/shout'...
remote: Counting objects: 66, done.
remote: Compressing objects: 100% (36/36), done.
remote: Total 66 (delta 24), reused 65 (delta 23)
Receiving objects: 100% (66/66), 11.16 KiB | 0 bytes/s, done.
Resolving deltas: 100% (24/24), done.
Checking connectivity... done.
$ cd tsnow/shout
git.3
$ git checkout -qf 12dcdbcf20dbcb57a17ae699d750b22716f0132e
$ rvm use 2.1-head --install --binary --fuzzy
ruby-2.1-head is not installed - installing.
Searching for binary rubies, this might take some time.
Requested binary installation but no rubies are available to download, consider skipping --binary flag.
Gemset '' does not exist, 'rvm ruby-2.1-head do rvm gemset create ' first, or append '--create'.
The command "rvm use 2.1-head --install --binary --fuzzy" failed and exited with 2 during .
Your build has been stopped.