bpo-41207 In distutils.spawn, rewrite FileNotFound (GH-21359)

Automerge-Triggered-By: @jaraco

spawn.py

@@ -71,9 +71,15 @@ def spawn(cmd, search_path=1, verbose=0, dry_run=0):
             env = dict(os.environ,
                        MACOSX_DEPLOYMENT_TARGET=cur_target)
 
-    proc = subprocess.Popen(cmd, env=env)
-    proc.wait()
-    exitcode = proc.returncode
+    try:
+        proc = subprocess.Popen(cmd, env=env)
+        proc.wait()
+        exitcode = proc.returncode
+    except OSError as exc:
+        if not DEBUG:
+            cmd = cmd[0]
+        raise DistutilsExecError(
+            "command %r failed: %s" % (cmd, exc.args[-1])) from exc
 
     if exitcode:
         if not DEBUG:

tests/test_spawn.py

@@ -124,6 +124,11 @@ class SpawnTestCase(support.TempdirManager,
                     rv = find_executable(program)
                     self.assertEqual(rv, filename)
 
+    def test_spawn_missing_exe(self):
+        with self.assertRaises(DistutilsExecError) as ctx:
+            spawn(['does-not-exist'])
+        self.assertIn("command 'does-not-exist' failed", str(ctx.exception))
+
 
 def test_suite():
     return unittest.makeSuite(SpawnTestCase)