rails/rails — pull request #8219 by nikitug (2012-11-14 12:44:45+00:00)
Title: Make XmlMini.with_backend usable with threads

`XmlMini.with_backend` now may be safely used with threads:

```ruby
Thread.new do
XmlMini.with_backend("REXML") { rexml_power }
end
Thread.new do
XmlMini.with_backend("LibXML") { libxml_power }
end
```

Each thread will use it's own backend.