Repl doesn't wait on incomplete assignment

[CertainLach]

Describe the bug

Previously, typing those two expressions in nix repl resulted in the same:

nix-repl> {[ENTER]

nix-repl> obj = {[ENTER]

I was able to continue typing

nix-repl> obj = {
        >    a = 1;
        > }

But d8b067b has broken it, and now only the first (non-assignment) expression wait for the output, assignment fails with an unexpected end of file error:

nix-repl> a = {  
error: syntax error, unexpected end of file, expecting INHERIT
       at «string»:1:3:
            1|  {
             |   ^

nix-repl> {
        >   a = 1;
        > }
{ a = 1; }

Metadata

Nix 2.30.1

Additional context

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

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