"Invalid gemspec" error

Running `puppet-library` results in the following error.

```
Invalid gemspec in [/Users/me/.rvm/gems/ruby-2.1.0@global/specifications/executable-hooks-1.3.1.gemspec]: wrong number of arguments (3 for 1..2)
```

Observed in 0.10.0, 0.11.0, and 0.12.0.
