[1.4.x] Clarified striptags documentation

The fact that striptags cannot guarantee to really strip all
non-safe HTML content was not clear enough. Also see:
https://www.djangoproject.com/weblog/2014/mar/22/strip-tags-advisory/

Partial backport (doc-only) of 6ca6c36f82 from master.

1 files changed, 11 insertions, 1 deletions

diff --git a/docs/ref/templates/builtins.txt b/docs/ref/templates/builtins.txt
index e911bb167b..e2734c9747 100644
--- a/docs/ref/templates/builtins.txt
+++ b/docs/ref/templates/builtins.txt
@@ -1988,7 +1988,7 @@ If ``value`` is ``"Joel is a slug"``, the output will be ``"Joel is a slug"``.
 striptags
 ^^^^^^^^^
 
-Strips all [X]HTML tags.
+Makes all possible efforts to strip all [X]HTML tags.
 
 For example::
 
@@ -1997,6 +1997,16 @@ For example::
 If ``value`` is ``"<b>Joel</b> <button>is</button> a <span>slug</span>"``, the
 output will be ``"Joel is a slug"``.
 
+.. admonition:: No safety guarantee
+
+    Note that ``striptags`` doesn't give any guarantee about its output being
+    entirely HTML safe, particularly with non valid HTML input. So **NEVER**
+    apply the ``safe`` filter to a ``striptags`` output.
+    If you are looking for something more robust, you can use the ``bleach``
+    Python library, notably its `clean`_ method.
+
+.. _clean: http://bleach.readthedocs.org/en/latest/clean.html
+
 .. templatefilter:: time
 
 time