title: Apt-get error "undefined symbol: xml_sethashsalt" when install/update python3
body: <p>It just keeps failing when I do <code>sudo apt-get upgrade</code> because it failed to upgrade some package that based on Python3. The error was: <code>undefined symbol: XML_SetHashSalt</code>. I'd been searching around for solutions but there is no such answer on StackOverflow.</p>
  
  <p>Then at the end, I found an answer on not very related question mention that the library path for <code>libexpat.so.1</code> pointing to <code>/usr/local/lib/</code> may cause the issue. So I try to rename <code>libexpat.so.1</code> to <code>libexpat.so.1-bk</code> then it works.</p>
  
  <p>So I just re-post it here, hope it helps for anyone facing it.</p>