Unable to use HTTP proxy handler in CouchDB's externals API

gistfile1.txt

Apache CouchDB 1.0.2 (LogLevel=debug) is starting.
Configuration Settings ["/etc/couchdb/default.ini","/etc/couchdb/local.ini"]:
  [async_mailer] port="9000"
  [attachments] compressible_types="text/*, application/javascript, application/json,  application/xml"
  [attachments] compression_level="8"
  [couch_httpd_auth] auth_cache_size="50"
  [couch_httpd_auth] authentication_db="_users"
  [couch_httpd_auth] authentication_redirect="/_utils/session.html"
  [couch_httpd_auth] require_valid_user="false"
  [couch_httpd_auth] secret="0c0cd567d2672d625bc8f493c9b2b354"
  [couch_httpd_auth] timeout="5000"
  [couchdb] database_dir="/var/lib/couchdb"
  [couchdb] delayed_commits="true"
  [couchdb] max_attachment_chunk_size="4294967296"
  [couchdb] max_dbs_open="100"
  [couchdb] max_document_size="4294967296"
  [couchdb] os_process_timeout="5000"
  [couchdb] uri_file="/var/lib/couchdb/couch.uri"
  [couchdb] util_driver_dir="/usr/lib/couchdb/erlang/lib/couch-1.0.2/priv/lib"
  [couchdb] view_index_dir="/var/lib/couchdb"
  [daemons] auth_cache="{couch_auth_cache, start_link, []}"
  [daemons] db_update_notifier="{couch_db_update_notifier_sup, start_link, []}"
  [daemons] external_manager="{couch_external_manager, start_link, []}"
  [daemons] httpd="{couch_httpd, start_link, []}"
  [daemons] query_servers="{couch_query_servers, start_link, []}"
  [daemons] stats_aggregator="{couch_stats_aggregator, start, []}"
  [daemons] stats_collector="{couch_stats_collector, start, []}"
  [daemons] uuids="{couch_uuids, start, []}"
  [daemons] view_manager="{couch_view, start_link, []}"
  [external] mailer="/usr/bin/node /etc/couchdb/local.d/sync_mailer/mailer.js"
  [httpd] allow_jsonp="false"
  [httpd] authentication_handlers="{couch_httpd_oauth, oauth_authentication_handler}, {couch_httpd_auth, cookie_authentication_handler}, {couch_httpd_auth, default_authentication_handler}"
  [httpd] bind_address="127.0.0.1"
  [httpd] default_handler="{couch_httpd_db, handle_request}"
  [httpd] max_connections="2048"
  [httpd] port="5984"
  [httpd] secure_rewrites="true"
  [httpd] vhost_global_handlers="_utils, _uuids, _session, _oauth, _users"
  [httpd_db_handlers] _changes="{couch_httpd_db, handle_changes_req}"
  [httpd_db_handlers] _compact="{couch_httpd_db, handle_compact_req}"
  [httpd_db_handlers] _design="{couch_httpd_db, handle_design_req}"
  [httpd_db_handlers] _mailer="{couch_httpd_external, handle_external_req, <<\"mailer\">>}"
  [httpd_db_handlers] _temp_view="{couch_httpd_view, handle_temp_view_req}"
  [httpd_db_handlers] _view_cleanup="{couch_httpd_db, handle_view_cleanup_req}"
  [httpd_design_handlers] _info="{couch_httpd_db,   handle_design_info_req}"
  [httpd_design_handlers] _list="{couch_httpd_show, handle_view_list_req}"
  [httpd_design_handlers] _rewrite="{couch_httpd_rewrite, handle_rewrite_req}"
  [httpd_design_handlers] _show="{couch_httpd_show, handle_doc_show_req}"
  [httpd_design_handlers] _update="{couch_httpd_show, handle_doc_update_req}"
  [httpd_design_handlers] _view="{couch_httpd_view, handle_view_req}"
  [httpd_global_handlers] /="{couch_httpd_misc_handlers, handle_welcome_req, <<\"Welcome\">>}"
  [httpd_global_handlers] _active_tasks="{couch_httpd_misc_handlers, handle_task_status_req}"
  [httpd_global_handlers] _all_dbs="{couch_httpd_misc_handlers, handle_all_dbs_req}"
  [httpd_global_handlers] _async_mailer="{couch_httpd_proxy, handle_proxy_req, <<\"http://127.0.0.1:9000\">>}"
  [httpd_global_handlers] _config="{couch_httpd_misc_handlers, handle_config_req}"
  [httpd_global_handlers] _google="{couch_httpd_proxy, handle_proxy_req, <<\"http://www.google.com\">>}"
  [httpd_global_handlers] _log="{couch_httpd_misc_handlers, handle_log_req}"
  [httpd_global_handlers] _oauth="{couch_httpd_oauth, handle_oauth_req}"
  [httpd_global_handlers] _replicate="{couch_httpd_misc_handlers, handle_replicate_req}"
  [httpd_global_handlers] _restart="{couch_httpd_misc_handlers, handle_restart_req}"
  [httpd_global_handlers] _session="{couch_httpd_auth, handle_session_req}"
  [httpd_global_handlers] _stats="{couch_httpd_stats_handlers, handle_stats_req}"
  [httpd_global_handlers] _utils="{couch_httpd_misc_handlers, handle_utils_dir_req, \"/usr/share/couchdb/www\"}"
  [httpd_global_handlers] _uuids="{couch_httpd_misc_handlers, handle_uuids_req}"
  [httpd_global_handlers] favicon.ico="{couch_httpd_misc_handlers, handle_favicon_req, \"/usr/share/couchdb/www\"}"
  [log] file="/var/log/couchdb/couch.log"
  [log] include_sasl="true"
  [log] level="debug"
  [os_daemons] async_mailer="/etc/couchdb/local.d/async_mailer/mailer.js"
  [query_server_config] reduce_limit="true"
  [query_servers] javascript="/usr/bin/couchjs /usr/share/couchdb/server/main.js"
  [replicator] max_http_pipeline_size="50"
  [replicator] max_http_sessions="20"
  [replicator] ssl_certificate_max_depth="3"
  [replicator] verify_ssl_certificates="false"
  [stats] rate="1000"
  [stats] samples="[0, 60, 300, 900]"
  [uuids] algorithm="sequential"
  [vhosts] blog.couchdb:5984="/blog/_design/blog/_rewrite"
Apache CouchDB has started. Time to relax.
[info] [<0.32.0>] Apache CouchDB has started on http://127.0.0.1:5984/
[debug] [<0.98.0>] 'GET' /_google/search?q=plankton {1,1}
Headers: [{'Accept',"*/*"},
          {'Host',"127.0.0.1:5984"},
          {'User-Agent',"curl/7.21.4 (x86_64-unknown-linux-gnu) libcurl/7.21.4 OpenSSL/1.0.0d zlib/1.2.5"}]
[debug] [<0.98.0>] OAuth Params: [{"q","plankton"}]
[error] [<0.98.0>] Uncaught error in HTTP request: {error,undef}
[info] [<0.98.0>] Stacktrace: [{couch_httpd_proxy,handle_proxy_req,
                 [{httpd,
                      {mochiweb_request,#Port<0.2067>,'GET',
                          "/_google/search?q=plankton",
                          {1,1},
                          {3,
                           {"user-agent",
                            {'User-Agent',
                                "curl/7.21.4 (x86_64-unknown-linux-gnu) libcurl/7.21.4 OpenSSL/1.0.0d zlib/1.2.5"},
                            {"host",
                             {'Host',"127.0.0.1:5984"},
                             {"accept",{'Accept',"*/*"},nil,nil},
                             nil},
                            nil}}},
                      "127.0.0.1",'GET',
                      [<<"_google">>,<<"search">>],
                      {dict,6,16,16,8,80,48,
                          {[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},
                          {{[[<<"_design">>|#Fun<couch_httpd.8.61263750>]],
                            [],
                            [[<<"_view_cleanup">>|
                              #Fun<couch_httpd.8.61263750>]],
                            [],[],[],[],[],
                            [[<<"_compact">>|#Fun<couch_httpd.8.61263750>]],
                            [],
                            [[<<"_mailer">>|#Fun<couch_httpd.7.73239249>]],
                            [[<<"_temp_view">>|#Fun<couch_httpd.8.61263750>]],
                            [[<<"_changes">>|#Fun<couch_httpd.8.61263750>]],
                            [],[],[]}}},
                      {user_ctx,null,[],undefined},
                      undefined,
                      {dict,6,16,16,8,80,48,
                          {[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},
                          {{[],
                            [[<<"_show">>|#Fun<couch_httpd.10.132977763>]],
                            [[<<"_info">>|#Fun<couch_httpd.10.132977763>],
                             [<<"_list">>|#Fun<couch_httpd.10.132977763>]],
                            [[<<"_update">>|#Fun<couch_httpd.10.132977763>]],
                            [],[],[],[],[],
                            [[<<"_rewrite">>|#Fun<couch_httpd.10.132977763>]],
                            [],[],[],
                            [[<<"_view">>|#Fun<couch_httpd.10.132977763>]],
                            [],[]}}},
                      undefined,#Fun<couch_httpd.6.96187723>,
                      {dict,15,16,16,8,80,48,
                          {[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},
                          {{[[<<"_restart">>|#Fun<couch_httpd.6.96187723>],
                             [<<"_replicate">>|#Fun<couch_httpd.6.96187723>]],
                            [[<<"_active_tasks">>|
                              #Fun<couch_httpd.6.96187723>]],
                            [],
                            [[<<"_async_mailer">>|
                              #Fun<couch_httpd.5.8198673>]],
                            [[<<"_utils">>|#Fun<couch_httpd.5.8198673>],
                             [<<"/">>|#Fun<couch_httpd.5.8198673>],
                             [<<"_config">>|#Fun<couch_httpd.6.96187723>]],
                            [[<<"_log">>|#Fun<couch_httpd.6.96187723>]],
                            [],[],
                            [[<<"_all_dbs">>|#Fun<couch_httpd.6.96187723>]],
                            [],
                            [[<<"favicon.ico">>|#Fun<couch_httpd.5.8198673>],
                             [<<"_stats">>|#Fun<couch_httpd.6.96187723>]],
                            [[<<"_session">>|#Fun<couch_httpd.6.96187723>],
                             [<<"_uuids">>|#Fun<couch_httpd.6.96187723>]],
                            [],[],
                            [[<<"_oauth">>|#Fun<couch_httpd.6.96187723>]],
                            [[<<"_google">>|#Fun<couch_httpd.5.8198673>]]}}}},
                  <<"http://www.google.com">>]},
             {couch_httpd,handle_request_int,5},
             {mochiweb_http,headers,5},
             {proc_lib,init_p_do_apply,3}]
[info] [<0.98.0>] 127.0.0.1 - - 'GET' /_google/search?q=plankton 500
[debug] [<0.98.0>] httpd 500 error response:
 {"error":"unknown_error","reason":"undef"}

My bad. This is not available on 1.0.2, but will be in 1.1.0.