Bad pretty printer for let bindings in a do-notation with braces

Let bindings in do-notations with braces like this:

module Thing where

thing = do {let {x = 1};
            print x}

get pretty printed with the braces around the bindings stripped, like this:

module Thing where

thing = do {let x = 1;
            print x}

Steps to reproduce: copy the module into Try.hs then call: ghc -ddump-rn Try.hs

I traced the code to: https://github.com/ghc/ghc/blob/e28fbbb7c3d5904a88b4743d0d10f212d61d8293/compiler/hsSyn/HsExpr.hs#L1929 which points to the pretty printer for list of declarations: https://github.com/ghc/ghc/blob/95dc6dc070deac733d4a4a63a93e606a2e772a67/compiler/hsSyn/HsBinds.hs#L492 Indeed there is a comment on the two ways to pretty print binders - without braces in multiple lines and with braces in one line. However the comment does not explain the choice, and as discussed in #13302 (closed) the former won't parse in a do-notation.

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