fixup! buildout.py: Optimize _install_and_load by using cache.

src/zc/buildout/buildout.py

@@ -1356,10 +1356,11 @@ _install_and_load_cache = {}
 def _install_and_load(spec, group, entry, buildout):
     __doing__ = 'Loading recipe %r.', spec
 
+    key = spec, group, entry
     try:
-      return _install_and_load_cache[(spec, group, entry)]
+        return _install_and_load_cache[key]
     except KeyError:
-      pass
+        pass
 
     try:
         req = pkg_resources.Requirement.parse(spec)
@@ -1387,9 +1388,8 @@ def _install_and_load(spec, group, entry, buildout):
                 )
 
         __doing__ = 'Loading %s recipe entry %s:%s.', group, spec, entry
-        result = pkg_resources.load_entry_point(
+        result = _install_and_load_cache[key] = pkg_resources.load_entry_point(
             req.project_name, group, entry)
-        _install_and_load_cache[(spec, group, entry)] = result
         return result
 
     except Exception: