Multiple return values / bug in rpart?

In the recommended package rpart (version 4.1-1), the file rpartpl.R
contains the following line:

return(x = x[!erase], y = y[!erase])

AFAIK, returning multiple values like this is not valid R. Is that
correct? I can't seem to make it work in my own code.

Works for me, returning a list:

 > foo
function(x){return(x,x*2)}
 > foo(99)
[[1]]
[1] 99

[[2]]
[1] 198

But hey, that might just be because I redefined 'return' earlier:

 > return
function(...){list(...)}

It is unlikely this is the case in rpart though...