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/term_util.vim b/src/testdir/term_util.vim
index d376a95..1a06db7 100644
--- a/src/testdir/term_util.vim
+++ b/src/testdir/term_util.vim
@@ -174,7 +174,7 @@
 " number.
 func Run_shell_in_terminal(options)
   if has('win32')
-    let buf = term_start([&shell, '/k'], a:options)
+    let buf = term_start([&shell, '/D', '/k'], a:options)
   else
     let buf = term_start(&shell, a:options)
   endif