DDT's cache stats hooks prevent cache.clear() working correctly

[andrewhayes1979]

Using:

• Django 1.8.2
• DDT 1.3.0
• memcached backend installed as 'default' in the CACHES setting

I have a link in the admin that calls a naked cache.clear() call to reset the 'default' cache back to empty.

If DDT is not installed/activated (middleware is not present), this works fine. The clear() call is routed through to django.core.cache.backends.memcached.MemcachedCache.clear(), as expected.

If DDT is installed, DDT installs stats hooks into the cache in order to capture cache call information...this is installed in the process_request() of the middleware.

The call to cache.clear() now gets routed through django.core.cache.backends.base.BaseCache.clear(), whereby a NotImplemented exception is raised

DDT is therefore not correctly routing calls to the cache through to the configured backend under all circumstances when it's hooks are installed.

[tim-schilling]

This was fixed by #712 and is in in version 1.3.2.