Fix a number of CI_Cache bugs

Fixes #4277
Supersedes #4474
Really fixes #4066
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 888ae5f..52e8d13 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -44,6 +44,8 @@
 -  Fixed a bug where :doc:`Database <database/index>` transactions didn't work with the 'ibase' driver.
 -  Fixed a bug (#4475) - :doc:`Security Library <libraries/security>` method ``strip_image_tags()`` preserves only the first URL character from non-quoted *src* attributes.
 -  Fixed a bug where :doc:`Profiler Library <general/profiling>` didn't apply ``htmlspecialchars()`` to all displayed inputs.
+-  Fixed a bug (#4277) - :doc:`Cache Library <libraries/caching>` triggered fatal errors if accessing the Memcache(d) and/or Redis driver and they are not available on the system.
+-  Fixed a bug where :doc:`Cache Library <libraries/caching>` method ``is_supported()`` logged an error message on when it returns ``FALSE`` for the APC and Wincache drivers.
 
 Version 3.0.4
 =============