Fix windows (thx to cross)

In case everyone else needs this: `cross check --target x86_64-pc-windows-gnu`

src/main.rs

@@ -271,15 +271,16 @@ fn detect_venv(target: &Target) -> Result<PathBuf> {
 #[cfg(feature = "maturin-run")]
 /// `maturin run` implementation. Looks for a virtualenv .venv in cwd or any parent and execve
 /// python from there with args
-fn python_run(mut args: Vec<String>) -> Result<()> {
+fn python_run(args: Vec<String>) -> Result<()> {
     // Not sure if it's even feasible to support other target triples here given the restrictions
     // with argument parsing
     let target = Target::from_target_triple(None)?;
     let venv_dir = detect_venv(&target)?;
     let python = target.get_venv_python(venv_dir);
-    debug!("launching (execv) {}", python.display());
     #[cfg(unix)]
     {
+        debug!("launching (execv) {}", python.display());
+        let mut args = args;
         // Sorry for all the to_string_lossy
         // https://stackoverflow.com/a/38948854/3549270
         let executable_c_str = CString::new(python.to_string_lossy().as_bytes())
@@ -306,8 +307,9 @@ fn python_run(mut args: Vec<String>) -> Result<()> {
     }
     #[cfg(windows)]
     {
+        debug!("launching (new process) {}", python.display());
         // TODO: What's the correct equivalent of execv on windows?
-        let status = std::process::Command::new(script_path)
+        let status = Command::new(python)
             .args(args.iter())
             .status()
             .context("Failed to launch process")?;