Erase async_open entry in failure case

COUCHDB-2749

Author: rnewson

src/couch_server.erl

@@ -375,6 +375,7 @@ handle_call({open_result, DbName, {ok, Db}}, {FromPid, _Tag}, Server) ->
 handle_call({open_result, DbName, {error, eexist}}, From, Server) ->
     handle_call({open_result, DbName, file_exists}, From, Server);
 handle_call({open_result, DbName, Error}, {FromPid, _Tag}, Server) ->
+    erase({async_open, DbName}),
     % icky hack of field values - compactor_pid used to store clients
     [#db{fd=ReqType, compactor_pid=Froms}=Db] = ets:lookup(couch_dbs, DbName),
     [gen_server:reply(From, Error) || From <- Froms],