patch 8.2.3739: in wrong directory when using win_execute() with 'acd' set

Problem:    In wrong directory when using win_execute() with 'acd' set.
Solution:   Restore the directory when returning to the window. (closes #9276)

src/testdir/test_autochdir.vim

@@ -25,6 +25,33 @@ func Test_set_filename()
   call delete('samples/Xtest')
 endfunc
 
+func Test_set_filename_other_window()
+  call ch_logfile('logfile', 'w')
+  let cwd = getcwd()
+  call test_autochdir()
+  call mkdir('Xa')
+  call mkdir('Xb')
+  call mkdir('Xc')
+  try
+    args Xa/aaa.txt Xb/bbb.txt
+    set acd
+    let winid = win_getid()
+    snext
+    call assert_equal('Xb', substitute(getcwd(), '.*/\([^/]*\)$', '\1', ''))
+    call win_execute(winid, 'file ' .. cwd .. '/Xc/ccc.txt')
+    call assert_equal('Xb', substitute(getcwd(), '.*/\([^/]*\)$', '\1', ''))
+  finally
+    set noacd
+    call chdir(cwd)
+    call delete('Xa', 'rf')
+    call delete('Xb', 'rf')
+    call delete('Xc', 'rf')
+    bwipe! aaa.txt
+    bwipe! bbb.txt
+    bwipe! ccc.txt
+  endtry
+endfunc
+
 func Test_verbose_pwd()
   let cwd = getcwd()
   call test_autochdir()
@@ -53,6 +80,8 @@ func Test_verbose_pwd()
   set noacd
   call assert_match('\[autochdir\].*testdir[/\\]Xautodir', execute('verbose pwd'))
   wincmd w
+  call assert_match('\[autochdir\].*testdir[/\\]Xautodir', execute('verbose pwd'))
+  execute 'cd' cwd
   call assert_match('\[global\].*testdir', execute('verbose pwd'))
   wincmd w
   call assert_match('\[window\].*testdir[/\\]Xautodir', execute('verbose pwd'))

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3739,
 /**/
     3738,
 /**/

src/window.c

@@ -4858,6 +4858,11 @@ win_enter_ext(win_T *wp, int flags)
     void
 fix_current_dir(void)
 {
+#ifdef FEAT_AUTOCHDIR
+    if (p_acd)
+	do_autochdir();
+    else
+#endif
     if (curwin->w_localdir != NULL || curtab->tp_localdir != NULL)
     {
 	char_u	*dirname;