Fatal error (operator not supported) when attempting to change user password

I get the following when trying to change my user password from the user edit form.

( ! ) Fatal error: [] operator not supported for strings in /home/tom/workspace/concern6/sites/all/modules/path_redirect/path_redirect.module on line 316
Call Stack
#	Time	Memory	Function	Location
1	0.0003	123352	{main}( )	../index.php:0
2	0.2809	41706456	menu_execute_active_handler( )	../index.php:18
3	0.2876	42340840	call_user_func_array ( )	../menu.inc:348
4	0.2876	42340840	user_edit( )	../menu.inc:0
5	0.2877	42341296	drupal_get_form( )	../user.pages.inc:235
6	0.3800	53039496	drupal_process_form( )	../form.inc:119
7	0.4124	55175968	form_execute_handlers( )	../form.inc:409
8	0.4125	55175968	user_profile_form_submit( )	../form.inc:769
9	0.4183	55179608	user_save( )	../user.pages.inc:288
10	0.4196	55181208	user_module_invoke( )	../user.module:214
11	0.4203	55182400	pathauto_user( )	../user.module:22
12	0.4860	55591784	pathauto_create_alias( )	../pathauto.module:425
13	0.4883	55591880	_pathauto_alias_exists( )	../pathauto.inc:306
14	0.4909	55592024	path_redirect_delete( )	../pathauto.inc:71