readline in function call with space in prompt.

Hello,

I have noticed a behavior that I don't understand. When I call the
following function from the prompt.
test <- function(){
    a <- readline("selection: ")
    a
}

test()
selection: |

I can only type one character and the readline function exits before I can
press enter.

however

test1 <- function(){
    a <- readline("selection:")
    a
}

test1()
selection:|

works as expected.

selection: abc[Ret]

However calling directly readline with a space in the prompt does what I
would expect.

a <- readline("selection: ")
selection: abc[Ret]
a
"abc"

It is the expected behavior or am I missing something?

Best regards,
Jeremie

Jeremie Juste
> R version 4.0.3 (2020-10-10)