clippy:clone_on_copy

warning: using `clone` on type `Option<&Vec<String>>` which implements the `Copy` trait
    --> src/util.rs:1091:64
     |
1091 |         let reserved_found = if let Some(reserved_names_vec) = reserved_names.clone() {
     |                                                                ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `reserved_names`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
     = note: `#[warn(clippy::clone_on_copy)]` on by default

src/util.rs

@@ -1088,7 +1088,7 @@ pub fn safe_header_names(
     let mut buf_wrk = String::new();
 
     for header_name in headers {
-        let reserved_found = if let Some(reserved_names_vec) = reserved_names.clone() {
+        let reserved_found = if let Some(reserved_names_vec) = reserved_names {
             if keep_case {
                 header_name.clone_into(&mut buf_wrk);
             } else {