vim-patch:8.1.0177: defining function in sandbox is inconsistent

Problem:    Defining function in sandbox is inconsistent, cannot use :function
            but can define a lambda.
Solution:   Allow defining a function in the sandbox, but also use the sandbox
            when executing it. (closes vim/vim#3182)
93343725b5

src/nvim/ex_cmds.lua

@@ -1004,7 +1004,7 @@ return {
   },
   {
     command='function',
-    flags=bit.bor(EXTRA, BANG, CMDWIN),
+    flags=bit.bor(EXTRA, BANG, SBOXOK, CMDWIN),
     addr_type=ADDR_LINES,
     func='ex_function',
   },