minstall: Fix signature of monkeypatched os.chown

this also clears up the last of the mypy problems in minstall, yay!

mesonbuild/minstall.py

@@ -124,10 +124,19 @@ def set_chown(path: str, user: T.Optional[str] = None, group: T.Optional[str] =
     # Not nice, but better than actually rewriting shutil.chown until
     # this python bug is fixed: https://bugs.python.org/issue18108
     real_os_chown = os.chown
+
+    def chown(path: T.Union[int, str, 'os.PathLike[str]', bytes, 'os.PathLike[bytes]'],
+              uid: int, gid: int, *, dir_fd: T.Optional[int] = dir_fd,
+              follow_symlinks: bool = follow_symlinks) -> None:
+        """Override the default behavior of os.chown
+
+        Use a real function rather than a lambda to help mypy out. Also real
+        functions are faster.
+        """
+        real_os_chown(path, gid, uid, dir_fd=dir_fd, follow_symlinks=follow_symlinks)
+
     try:
-        os.chown = lambda p, u, g: real_os_chown(p, u, g,
-                                                 dir_fd=dir_fd,
-                                                 follow_symlinks=follow_symlinks)
+        os.chown = chown
         shutil.chown(path, user, group)
     finally:
         os.chown = real_os_chown