update to 1.5.17
    
    - Update py-compile to current upstream version
    - Also use ＿ U+FF3F FULLWIDTH LOW LINE as a separator for emoji keywords
    - Unbreak sqlite on Python 3.6 (thanks to Jan Alexander Steffens)
    - Return immediately if _update_candidates() is called with
      empty input (Resolves: rhbz#1413082)