refactor: pull out opt_index_or_registry in resolve_registry_or_index()

Author: motorailgun

src/cargo/ops/registry/publish.rs

@@ -799,7 +799,9 @@ fn resolve_registry_or_index(
     opts: &PublishOpts<'_>,
     just_pkgs: &[&Package],
 ) -> CargoResult<Option<RegistryOrIndex>> {
-    Ok(match opts.reg_or_index.clone() {
+    let opt_index_or_registry = opts.reg_or_index.clone();
+
+    Ok(match opt_index_or_registry {
         Some(r) => {
             validate_registry(&just_pkgs, Some(&r))?;
             Some(r)