failed couchdb attachment curl PUT

gistfile1.erl

[info] [<0.1291.8>] 127.0.0.1 - - HEAD /test/test 200
 {1,ug] [<0.1292.8>] 'PUT' /test/test/thumbs/small/181.png?rev=895-d11d3854fee8e91b8be879ed79e50192
                                                                                                      1} from "127.0.0.1"
Headers: [{'Accept',"*/*"},
          {'Host',"localhost:5984"},
          {'User-Agent',"curl/7.22.0 (x86_64-pc-linux-gnu) libcurl/7.22.0 OpenSSL/1.0.1 zlib/1.2.3.4 libidn/1.23 librtmp/2.3"}]
[debug] [<0.1292.8>] OAuth Params: [{"rev",
                                     "895-d11d3854fee8e91b8be879ed79e50192\r"}]
[debug] [<0.1292.8>] Minor error in HTTP request: conflict
[debug] [<0.1292.8>] Stacktrace: [{couch_httpd_db,db_attachment_req,4,
                                   [{file,
                                     "/home/paul/build-couchdb/dependencies/couchdb/src/couchdb/couch_httpd_db.erl"},
                                    {line,1176}]},
                                  {couch_httpd_db,do_db_req,2,
                                   [{file,
                                     "/home/paul/build-couchdb/dependencies/couchdb/src/couchdb/couch_httpd_db.erl"},
                                    {line,230}]},
                                  {couch_httpd,handle_request_int,5,
                                   [{file,
                                     "/home/paul/build-couchdb/dependencies/couchdb/src/couchdb/couch_httpd.erl"},
                                    {line,317}]},
                                  {mochiweb_http,headers,5,
                                   [{file,
                                     "/home/paul/build-couchdb/dependencies/couchdb/src/mochiweb/mochiweb_http.erl"},
                                    {line,136}]},
                                  {proc_lib,init_p_do_apply,3,
                                   [{file,"proc_lib.erl"},{line,227}]}]
[info] [<0.1292.8>] 127.0.0.1 - - PUT /test/test/thumbs/small/181.png?rev=895-d11d3854fee8e91b8be879ed79e 4092
[debug] [<0.1292.8>] httpd 409 error response:
 {"error":"conflict","reason":"Document update conflict."}