patch 9.1.0794: tests: tests may fail on Windows environment

Problem:  tests: tests may fail on Windows environment
Solution: use shellcmdflag=/D to skip executing autorun from
          the registry (Milly)

closes: #15900

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 31ebc1b..531aa6b 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -89,7 +89,7 @@
     let g:triggered = 0
     au CursorHoldI * let g:triggered += 1
     set updatetime=100
-    call job_start(has('win32') ? 'cmd /c echo:' : 'echo',
+    call job_start(has('win32') ? 'cmd /D /c echo:' : 'echo',
           \ {'exit_cb': {-> timer_start(200, 'ExitInsertMode')}})
     call feedkeys('a', 'x!')
     call assert_equal(1, g:triggered)