patch 8.2.0335: no completion for :disassemble

Problem:    No completion for :disassemble.
Solution:   Make completion work.  Also complete script-local functions if the
            name starts with "s:".
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 1baed79..8c58026 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -559,6 +559,17 @@
   delcommand Foo
 endfunc
 
+func s:ScriptLocalFunction()
+  echo 'yes'
+endfunc
+
+func Test_cmdline_complete_user_func()
+  call feedkeys(":func Test_cmdline_complete_user\<Tab>\<Home>\"\<cr>", 'tx')
+  call assert_match('"func Test_cmdline_complete_user', @:)
+  call feedkeys(":func s:ScriptL\<Tab>\<Home>\"\<cr>", 'tx')
+  call assert_match('"func <SNR>\d\+_ScriptLocalFunction', @:)
+endfunc
+
 func Test_cmdline_complete_user_names()
   if has('unix') && executable('whoami')
     let whoami = systemlist('whoami')[0]