-------------------------------

**Security fixes**

* Attributes that have URI values weren't properly sanitized if the
  values contained character entities. Using character entities, it
  was possible to construct a URI value with a scheme that was not
  allowed that would slide through unsanitized.

  This security issue was introduced in Bleach 2.1. Anyone using
  Bleach 2.1 is highly encouraged to upgrade.

**Backwards incompatible changes**

None

**Features**

None

**Bug fixes**

* Fixed some other edge cases for attribute URI value sanitizing and
  improved testing of this code.