util.human.io: Fix handling of os.execute() return values in Lua 5.2+
Wrong part of Lua 5.1 compat removed in 0f4feaf9ca64
For full information on our dependencies, version requirements, and
where to find them, see https://prosody.im/doc/depends
If you have luarocks available on your platform, install the following:
- luaexpat
- luasocket
- luafilesystem
- luasec