Do not initialize the Python interpreter if no filter is installed.

--- a/innd/python.c
+++ b/innd/python.c
@@ -684,7 +684,7 @@ PYreadfilter(void)
     PyObject	*result;
 
     if (!Py_IsInitialized()) {
-	syslog(L_ERROR, "python is not initialized");
+	syslog(L_NOTICE, "python is not initialized");
 	return 0;
     }
 
@@ -740,6 +740,14 @@ PYsetup(void)
 {
     const ARTHEADER *hp;
     size_t hdrcount;
+    char *path;
+
+    path = concatpath(innconf->pathfilter, INN_PATH_PYTHON_STARTUP);
+    if (access(path, R_OK) < 0) {
+	syslog(L_NOTICE, "%s not installed", path);
+	PYfilter(false);
+	return;
+    }
 
     /* Add path for innd module.  The environment variable PYTHONPATH
      * does it; one can also append innconf->pathfilter to sys.path once
--- a/nnrpd/python.c
+++ b/nnrpd/python.c
@@ -396,6 +396,8 @@ PY_access(char* file, struct vector *acc
 void
 PY_dynamic_init (char* file)
 {
+  if (!access(file, R_OK))
+      return;
   dynamic_file = xstrdup(file);
   PY_use_dynamic = true;
 }
