gnu: Add ruby-safe-yaml.

* gnu/packages/ruby.scm (ruby-safe-yaml): New variable.

gnu/packages/ruby.scm

@@ -5765,3 +5765,26 @@ (define-public ruby-heredoc-unindent
 strings are to be used otherwise, be it for printing or testing, the extra
 indentation will probably be an issue and hence this gem.")
     (license license:expat)))
+
+(define-public ruby-safe-yaml
+  (package
+    (name "ruby-safe-yaml")
+    (version "1.0.4")
+    (source (origin
+              (method url-fetch)
+              (uri (rubygems-uri "safe_yaml" version))
+              (sha256
+               (base32
+                "1hly915584hyi9q9vgd968x2nsi5yag9jyf5kq60lwzi5scr7094"))))
+    (build-system ruby-build-system)
+    (native-inputs
+     `(("ruby-rspec" ,ruby-rspec)
+       ("ruby-hashie" ,ruby-hashie)
+       ("ruby-heredoc-unindent" ,ruby-heredoc-unindent)))
+    (arguments `(#:test-target "spec"
+                 #:tests? #f));; FIXME: one failure
+    (home-page "https://github.com/dtao/safe_yaml")
+    (synopsis "YAML parser")
+    (description "The SafeYAML gem provides an alternative implementation of
+YAML.load suitable for accepting user input in Ruby applications.")
+    (license license:expat)))