Clippy nits while hacking around (#737)

* clippy: unnecessary guard

* create merge nix config clippy nit, old

* Clean up a clippy nit on an extra clone

* clippy nit legacy wsl detection error

src/action/base/create_or_merge_nix_config.rs

@@ -412,7 +412,7 @@ impl Action for CreateOrMergeNixConfig {
         new_config
             .push_str("# Generated by https://github.com/DeterminateSystems/nix-installer.\n");
         new_config.push_str("# See `/nix/nix-installer --version` for the version details.\n");
-        new_config.push_str("\n");
+        new_config.push('\n');
 
         for (name, value) in merged_nix_config.settings() {
             new_config.push_str(name);

src/action/common/configure_init_service.rs

@@ -169,7 +169,7 @@ impl Action for ConfigureInitService {
             #[cfg(target_os = "macos")]
             InitSystem::Launchd => {
                 let src = std::path::Path::new(DARWIN_NIX_DAEMON_SOURCE);
-                tokio::fs::copy(src.clone(), DARWIN_NIX_DAEMON_DEST)
+                tokio::fs::copy(src, DARWIN_NIX_DAEMON_DEST)
                     .await
                     .map_err(|e| {
                         Self::error(ActionErrorKind::Copy(

src/diagnostics.rs

@@ -261,7 +261,7 @@ pub fn diagnostic_endpoint_parser(input: &str) -> Result<Option<Url>, Diagnostic
             "https" | "http" | "file" => Ok(Some(v)),
             _ => Err(DiagnosticError::UnknownUrlScheme),
         },
-        Err(url_error) if url_error == url::ParseError::RelativeUrlWithoutBase => {
+        Err(url::ParseError::RelativeUrlWithoutBase) => {
             match Url::parse(&format!("file://{input}")) {
                 Ok(v) => Ok(Some(v)),
                 Err(file_error) => Err(file_error)?,

src/planner/linux.rs

@@ -220,9 +220,9 @@ pub(crate) async fn check_nix_not_already_installed() -> Result<(), PlannerError
 pub(crate) fn check_systemd_active() -> Result<(), PlannerError> {
     if !Path::new("/run/systemd/system").exists() {
         if std::env::var("WSL_DISTRO_NAME").is_ok() {
-            return Err(LinuxErrorKind::Wsl2SystemdNotActive)?;
+            return Err(LinuxErrorKind::Wsl2SystemdNotActive.into());
         } else {
-            return Err(LinuxErrorKind::SystemdNotActive)?;
+            return Err(LinuxErrorKind::SystemdNotActive.into());
         }
     }