patch 9.1.0684: completion is inserted on Enter with "noselect"

Problem:  completion is inserted on Enter with "noselect"
          (Carman Fu)
Solution: check noselect before update compl_shown_match
          (glepnir)

fixes: #15526
closes: #15530

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
index becd0d8..aee3393 100644
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -2654,6 +2654,13 @@
   call feedkeys("Su\<C-X>\<C-L>\<C-P>\<Esc>0", 'tx!')
   call assert_equal('no one can save me but you', getline('.'))
 
+  " issue #15526
+  set completeopt=fuzzy,menuone,menu,noselect
+  call setline(1, ['Text', 'ToText', ''])
+  call cursor(2, 1)
+  call feedkeys("STe\<C-X>\<C-N>x\<CR>\<Esc>0", 'tx!')
+  call assert_equal('Tex', getline('.'))
+
   " clean up
   set omnifunc=
   bw!