patch 8.2.1997: window changes when using bufload() while in a terminal popup

Problem:    Window changes when using bufload() while in a terminal popup.
Solution:   When searching for a window by ID also find a popup window.
            (closes #7307)
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 7d6bdbc..7351647 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -1237,6 +1237,23 @@
   unlet s:winid
 endfunc
 
+func Test_terminal_popup_bufload()
+  let termbuf = term_start(&shell, #{hidden: v:true, term_finish: 'close'})
+  let winid = popup_create(termbuf, {})
+  sleep 50m
+
+  let newbuf = bufadd('')
+  call bufload(newbuf)
+  call setbufline(newbuf, 1, 'foobar')
+
+  " must not have switched to another window
+  call assert_equal(winid, win_getid())
+
+  call feedkeys("exit\<CR>", 'xt')
+  sleep 50m
+  exe 'bwipe! ' .. newbuf
+endfunc
+
 func Test_terminal_popup_insert_cmd()
   CheckUnix
 
diff --git a/src/version.c b/src/version.c
index 7aadd45..0e9973e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1997,
+/**/
     1996,
 /**/
     1995,
diff --git a/src/window.c b/src/window.c
index 501ea84..1134d0a6 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1462,6 +1462,7 @@
 
 /*
  * Find window "id" in the current tab page.
+ * Also find popup windows.
  * Return NULL if not found.
  */
     win_T *
@@ -1472,6 +1473,14 @@
     FOR_ALL_WINDOWS(wp)
 	if (wp->w_id == id)
 	    return wp;
+#ifdef FEAT_PROP_POPUP
+    FOR_ALL_POPUPWINS(wp)
+	if (wp->w_id == id)
+	    return wp;
+    FOR_ALL_POPUPWINS_IN_TAB(curtab, wp)
+	if (wp->w_id == id)
+	    return wp;
+#endif
     return NULL;
 }