patch 9.0.0325: MS-Windows: completion test fails

Problem:    MS-Windows: completion test fails.
Solution:   Adjust directory prefix.
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
index 2ec2a5e..41998aa 100644
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -441,29 +441,29 @@
   set noshellslash
 
   set completeslash=
-  exe "normal oXd\<C-X>\<C-F>"
+  exe "normal oXcp\<C-X>\<C-F>"
   call assert_equal('Xcpldir\', getline('.'))
 
   set completeslash=backslash
-  exe "normal oXd\<C-X>\<C-F>"
+  exe "normal oXcp\<C-X>\<C-F>"
   call assert_equal('Xcpldir\', getline('.'))
 
   set completeslash=slash
-  exe "normal oXd\<C-X>\<C-F>"
+  exe "normal oXcp\<C-X>\<C-F>"
   call assert_equal('Xcpldir/', getline('.'))
 
   set shellslash
 
   set completeslash=
-  exe "normal oXd\<C-X>\<C-F>"
+  exe "normal oXcp\<C-X>\<C-F>"
   call assert_equal('Xcpldir/', getline('.'))
 
   set completeslash=backslash
-  exe "normal oXd\<C-X>\<C-F>"
+  exe "normal oXcp\<C-X>\<C-F>"
   call assert_equal('Xcpldir\', getline('.'))
 
   set completeslash=slash
-  exe "normal oXd\<C-X>\<C-F>"
+  exe "normal oXcp\<C-X>\<C-F>"
   call assert_equal('Xcpldir/', getline('.'))
   %bw!
   call delete('Xcpldir', 'rf')