patch 8.0.0127
Problem:    Cancelling completion still inserts text when formatting is done
            for 'textwidth'. (lacygoill)
Solution:   Don't format when CTRL-E was typed. (Hirohito Higashi,
            closes #1312)
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index f1e2c98..96c8d7e 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -464,4 +464,22 @@
   set completeopt&
 endfunc
 
+" <C-E> - select original typed text before the completion started without
+" auto-wrap text.
+func Test_completion_ctrl_e_without_autowrap()
+  new
+  let tw_save=&tw
+  set tw=78
+  let li = [
+        \ '"                                                        zzz',
+        \ '" zzzyyyyyyyyyyyyyyyyyyy']
+  call setline(1, li)
+  0
+  call feedkeys("A\<C-X>\<C-N>\<C-E>\<Esc>", "tx")
+  call assert_equal(li, getline(1, '$'))
+
+  let &tw=tw_save
+  q!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab