Merge #781: feat: optimize pushbytes by removing unreachable minimal …

…check

84d1ad5 feat: optimize pushbytes by removing unreachable minimal check (ChrisCho-H)

Pull request description:

  In [rust-bitcoin](https://github.com/rust-bitcoin/rust-bitcoin/blob/aa25adfc64ea0d742ca202991140f280024aba1b/bitcoin/src/blockdata/script/push_bytes.rs#L312), `read_scriptint` checks `NonMinimalPush`, which makes an additional minimal check needless and `PushBytes` inefficient.

ACKs for top commit:
  apoelstra:
    ACK 84d1ad5; successfully ran local tests; yep, I think you are right

Tree-SHA512: d16a199fd5caef13b4fa78584d61c7feb843accb2097b29ca7ccdabfd1cae3e5af9d54d70dc7b7b93f50809c2719f70a87cf4dbba9da53ed55d427568de9eed2

src/miniscript/lex.rs

@@ -213,14 +213,9 @@ pub fn lex(script: &'_ script::Script) -> Result<Vec<Token<'_>>, Error> {
                     33 => ret.push(Token::Bytes33(bytes.as_bytes())),
                     65 => ret.push(Token::Bytes65(bytes.as_bytes())),
                     _ => {
+                        // check minimality of the number
                         match script::read_scriptint(bytes.as_bytes()) {
                             Ok(v) if v >= 0 => {
-                                // check minimality of the number
-                                if script::Builder::new().push_int(v).into_script()[1..].as_bytes()
-                                    != bytes.as_bytes()
-                                {
-                                    return Err(Error::InvalidPush(bytes.to_owned().into()));
-                                }
                                 ret.push(Token::Num(v as u32));
                             }
                             Ok(_) => return Err(Error::InvalidPush(bytes.to_owned().into())),