SSL certificate validation errors with pre-built Yosemite ruby-2.1.5 binary

I installed the [pre-built binary ruby-2.1.5](https://rvm.io/binaries/osx/10.10/x86_64/ruby-2.1.5.tar.bz2) via the latest stable RVM on my Yosemite box. I'm having problems connecting to the [PuppetLabs forge](https://forgeapi.puppetlabs.com) with SSL certificate validation errors:

```
AtrisoBook:idalko-cibg ringods$ librarian-puppet install
/usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:920:in `connect': SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (Faraday::SSLError)
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:920:in `block in connect'
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/timeout.rb:76:in `timeout'
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:920:in `connect'
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:863:in `do_start'
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:852:in `start'
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:1369:in `request'
	from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/2.1.0/net/http.rb:1128:in `get'
	...
```

When using a ruby 2.1.4 built from source, I don't have these problems. Which certificates are used by the pre-built binary version?