Pre-load imports and templates for wsgi

This triggers preloading once in __init__ doing essentially the same
thing as in __call__. This avoids burdening the first request with the
startup cost. Fixes issue2551112.
Thanks to Robert Klonner for the patch.

Author: schlatterbeck

roundup/cgi/wsgi_handler.py

@@ -84,6 +84,9 @@ def __init__(self, home, debug=False, timing=False, lang=None):
                 tracker_home=home)
         else:
             self.translator = None
+        # trigger pre-loading of imports and templates
+        with self.get_tracker():
+            pass
 
     def __call__(self, environ, start_response):
         """Initialize with `apache.Request` object"""