patch 8.1.2295: if buffer of popup is in another window cursorline sign shows

Problem:    If buffer of popup is in another window cursorline sign shows.
Solution:   Check the group of the sign.
diff --git a/src/testdir/dumps/Test_popupwin_cursorline_8.dump b/src/testdir/dumps/Test_popupwin_cursorline_8.dump
new file mode 100644
index 0000000..51a009a
--- /dev/null
+++ b/src/testdir/dumps/Test_popupwin_cursorline_8.dump
@@ -0,0 +1,10 @@
+>o+0&#ffffff0|n|e| @71
+|t|w|o| @71
+|t|h|r|e@1| @69
+|~+0#4040ff13&| @33|o+0#0000001#ffd7ff255|n|e| @1| +0#4040ff13#ffffff0@34
+|~| @33|t+0#0000001#e0e0e08|w|o| @1| +0#4040ff13#ffffff0@34
+|~| @33|t+0#0000001#ffd7ff255|h|r|e@1| +0#4040ff13#ffffff0@34
+|~| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|1|,|1| @10|A|l@1| 
diff --git a/src/testdir/test_popupwin.vim b/src/testdir/test_popupwin.vim
index 7e94041..4992837 100644
--- a/src/testdir/test_popupwin.vim
+++ b/src/testdir/test_popupwin.vim
@@ -2615,6 +2615,23 @@
   call StopVimInTerminal(buf)
 
   call delete('XtestPopupCursorLine')
+
+  " ---------
+  " Use current buffer for popupmenu
+  " ---------
+  let lines =<< trim END
+    call setline(1, ['one', 'two', 'three'])
+    let winid = popup_create(bufnr('%'), #{
+	  \ cursorline : 1,
+	  \ })
+    call win_execute(winid, "2")
+  END
+  call writefile(lines, 'XtestPopupCursorLine')
+  let buf = RunVimInTerminal('-S XtestPopupCursorLine', #{rows: 10})
+  call VerifyScreenDump(buf, 'Test_popupwin_cursorline_8', {})
+  call StopVimInTerminal(buf)
+
+  call delete('XtestPopupCursorLine')
 endfunc
 
 func Test_previewpopup()