Index: subversion/bindings/swig/svn_client.i
===================================================================
--- subversion/bindings/swig/svn_client.i	(revision 15146)
+++ subversion/bindings/swig/svn_client.i	(working copy)
@@ -121,11 +121,14 @@
    svn_client_ctx_t
 */
 
-%typemap(python,in) (svn_client_get_commit_log_t log_msg_func, 
-                     void *log_msg_baton) {
+%typemap(python,in) (svn_client_get_commit_log_t log_msg_func)
+{
 
-  $1 = svn_swig_py_get_commit_log_func;
-  $2 = $input; /* our function is the baton. */
+  /* Assume that arg1 is svn_client_ctx_t. */
+  if (arg1) {
+    $1 = svn_swig_py_get_commit_log_func;
+    arg1->log_msg_baton = (void *)$input;
+  }
 }
 
 %typemap(ruby,in) (svn_client_get_commit_log_t log_msg_func)