Make XmlMini.with_backend usable with threads

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

  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.

1 files changed, 13 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 7daa0d5bca..b4c49918d1 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,5 +1,18 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   `XmlMini.with_backend` now may be safely used with threads:
+
+        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.
+
+    *Nikita Afanasenko*
+
 *   Dependencies no longer trigger Kernel#autoload in remove_const [fixes #8213]. *Xavier Noria*
 
 *   Simplify mocha integration and remove monkey-patches, bumping mocha to 0.13.0. *James Mead*