titlecase: unintended behavior with separators

[henry-oberholtzer]

The separator in the titlecase plugin, when combined with a replace config can consume characters after a string.

Problem

 Match (94.8%):
  Justin Timberlake - FutureSex/LoveSounds
  ≠ tracks
  MusicBrainz, CD, 2006, DE, Jive, 82876 87068 2, explicit
  https://musicbrainz.org/release/4cd6177f-9615-436e-a3ad-590c185d365d
  * Artist: Justin Timberlake
  * Album: FutureSex/LoveSounds
...
     ≠ (#6) What Goes                  (7:28) -> (#6) What Goes Around.../Omes     (7:28)
            Around.../...Comes Around                 Around (Interlude)
            (Interlude)
...
➜ [A]pply, More candidates, Skip, Use as-is, as Tracks, Group albums,
Enter search, enter Id, aBort, Print tracks, Open files with Picard? s

With the config for titlecase:

titlecase:
  separators: ["/"]

Disabling this config line resolved the issue, giving the proper track title of "What Goes Around.../...Comes Around (Interlude)"