/users/nonexisting and /vhosts/nonexisting crashes

[amr]

$ curl -i "http://localhost:9999/users/nonexisting" returns: "curl: (52) Empty reply from server"

And the following error in Alice shell:

(alice@pipeline)1> Error: {function_clause,
[{mochijson2,'-json_encode_proplist/2-fun-0-',
[{ok,400,[],{"nonexisting",<<"not a user">>}},
"{",
{encoder,null,false}]},
{lists,foldl,3},
{mochijson2,json_encode_proplist,2},
{rest_server,jsonify,1},
{rest_server,run_controller,4},
{mochiweb_http,headers,5},
{proc_lib,init_p_do_apply,3}]}

=CRASH REPORT==== 3-May-2010::00:51:02 ===
crasher:
initial call: mochiweb_socket_server:acceptor_loop/1
pid: <0.147.0>
registered_name: []
exception error: bad argument
in function iolist_size/1
called as iolist_size({ok,400,[],{"nonexisting",<<"not a user">>}})
in call from mochiweb_request:respond/2
in call from mochiweb_http:headers/5
ancestors: [mochiweb_http,rest_server,rest_server_sup,<0.59.0>,<0.58.0>]
messages: []
links: [<0.70.0>,#Port<0.892>]
dictionary: []
trap_exit: false
status: running
heap_size: 987
stack_size: 24
reductions: 888
neighbours:

=ERROR REPORT==== 3-May-2010::00:51:02 ===
{mochiweb_socket_server,235,{child_error,badarg}}

An identical behavior can be seen with /vhosts/nonexisting