Merge branch 'master' of github.com:mitsuhiko/jinja2

diff --cc CHANGES
index 69ed450822c88e8b325164a564814f4578df2275,0c2e125efadd2a5801223aef2d29bb057e38d918..c7b5f876e99dbe6b31a922bdf2ed6f90624d8a0a
--- 1/CHANGES
--- 2/CHANGES
+++ b/CHANGES
@@@ -4,8 -4,10 +4,10 @@@ Jinja2 Changelo
  Version 2.9
  -----------
  
 -(unreleased feature release)
 -
+ - Change cache key definition in environment. This fixes a performance
+   regression introduced in 2.8.
 +- Added support for `generator_stop` on supported Python versions
 +  (Python 3.5 and later)
  
  Version 2.8.1
  -------------