Up argument '= model.save' needs to be a number error -- Debugging in server - Rails 3, 1.9.2

When I am debugging in the server on Rails 3/1.9.2 I can not seem to assign a model object to a value:

(rdb:1) u = User.new(:email => “a@b.com”, :password => “password1”).save
Up argument ‘= User.new(:email => “a@b.com”, :password => “password1”).save’ needs to be a number.

But I can do:
(rdb:1) a = 1
1
(rdb:1)

And I can do:
(rdb:1) str = String
String
(rdb:1) str
String

Is this something to do with ActiveRecord perhaps, and if so is there a way to do this. For example I want to assign the model in the first example to a variable so I can ask for the errors.

Thanks,

David

Never mind, it seems that I can not assign to a single char variable in the debugger:

u = User.new

But I can do

user = User.new

That is because 'up' is a debugger command, and 'u' is the short form
of this command. So the debugger assumes you want the command u with
parameter = User.new.

If you want to use the variable u you can say
eval u=User.new
or
e u=User.new

Type help in the debugger to see all the commands.
The only reason that you can type things like user=User.new is because
autoeval has been set via
set autoeval

Colin