patch 8.2.4710: smart indenting does not work after completion

Problem:    Smart indenting does not work after completion.
Solution:   Set "can_si". (Christian Brabandt, closes #10113, closes #558)
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
index 3712abe..75ec03c 100644
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -2132,4 +2132,23 @@
   %bw!
 endfunc
 
+func FooBarComplete(findstart, base)
+  if a:findstart
+    return col('.') - 1
+  else
+    return ["Foo", "Bar", "}"]
+  endif
+endfunc
+
+func Test_complete_smartindent()
+  new
+  setlocal smartindent completefunc=FooBarComplete
+
+  exe "norm! o{\<cr>\<c-x>\<c-u>\<c-p>}\<cr>\<esc>"
+  let result = getline(1,'$')
+  call assert_equal(['', '{','}',''], result)
+  bw!
+  delfunction! FooBarComplete
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab