patch 8.2.3935: CTRL-U in Insert mode does not fix the indent

Problem:    CTRL-U in Insert mode does not fix the indent.
Solution:   Fix the indent when 'cindent' is set.
diff --git a/src/testdir/test_textformat.vim b/src/testdir/test_textformat.vim
index 1a7bb68..ccfd36f 100644
--- a/src/testdir/test_textformat.vim
+++ b/src/testdir/test_textformat.vim
@@ -238,7 +238,7 @@
   END
   call assert_equal(expected, getline(1, '$'))
 
-  " Using "o" repeates the line comment, "O" does not.
+  " Using "o" repeats the line comment, "O" does not.
   %del
   let text =<< trim END
       nop;
@@ -261,6 +261,21 @@
   END
   call assert_equal(expected, getline(1, '$'))
 
+  " Using CTRL-U after "o" fixes the indent
+  %del
+  let text =<< trim END
+      {
+         val = val;      // This is a comment
+  END
+  call setline(1, text)
+  exe "normal! 2Go\<C-U>x\<Esc>"
+  let expected =<< trim END
+      {
+         val = val;      // This is a comment
+         x
+  END
+  call assert_equal(expected, getline(1, '$'))
+
   bwipe!
 endfunc