patch 9.0.0650: some tests are failing

Problem:    Some tests are failing.
Solution:   Adjust for "<<<" showing up.
diff --git a/src/testdir/test_display.vim b/src/testdir/test_display.vim
index af18b7e..7237ed8 100644
--- a/src/testdir/test_display.vim
+++ b/src/testdir/test_display.vim
@@ -143,7 +143,7 @@
 
   let lines = ScreenLines([1,10], winwidth(0)+1)
   let expect = [
-        \ "<aaa aaa a|",
+        \ "<<<a aaa a|",
         \ "a aaa aaa |",
         \ "aa aaa aaa|",
         \ " aa aaa aa|",