Redundant checks in my_compiler.spawn (reduces distutils usage)

setup.py

@@ -30,7 +30,6 @@
 import os
 import platform
 import re
-import shutil
 import sys
 import winreg
 from collections.abc import MutableSequence
@@ -903,31 +902,24 @@ def key_reverse_mc(a):
         return MSVCCompiler.compile(self, sources, **kwargs)
 
     def spawn(self, cmd: MutableSequence[str]) -> None:  # type: ignore[override] # More restrictive than supertype
-        is_link = cmd[0].endswith("link.exe") or cmd[0].endswith('"link.exe"')
         is_mt = cmd[0].endswith("mt.exe") or cmd[0].endswith('"mt.exe"')
-        if is_mt:
-            # We don't want mt.exe run...
-            return
+        assert not is_mt, (
+            "We don't want mt.exe run. We used to special case it,"
+            + " now just sanity check that this is unreachable"
+        )
+        is_link = cmd[0].endswith("link.exe") or cmd[0].endswith('"link.exe"')
         if is_link:
             # remove /MANIFESTFILE:... and add MANIFEST:NO
             for i in range(len(cmd)):
                 if cmd[i].startswith(("/MANIFESTFILE:", "/MANIFEST:EMBED")):
                     cmd[i] = "/MANIFEST:NO"
                     break
-        if is_mt:
-            # We want mt.exe run with the original manifest
-            for i in range(len(cmd)):
-                if cmd[i] == "-manifest":
-                    cmd[i + 1] += ".orig"
-                    break
         super().spawn(cmd)  # type: ignore[arg-type] # mypy variance issue, but pyright ok
         if is_link:
-            # We want a copy of the original manifest so we can use it later.
-            for i in range(len(cmd)):
-                if cmd[i].startswith("/MANIFESTFILE:"):
-                    mfname = cmd[i][14:]
-                    shutil.copyfile(mfname, mfname + ".orig")
-                    break
+            assert not any(arg.startswith("/MANIFESTFILE:") for arg in cmd), (
+                "We used to copy the original manifest so we can use it later,"
+                + " now just sanity check that this is unreachable"
+            )
 
     # CCompiler's implementations of these methods completely replace the values
     # determined by the build environment. This seems like a design that must