plparse: Fix locking bug when ignoring schemes
plparse: Fix locking bug when ignoring schemes

Follow-up to edd1c84a548d402d7e7fde8c3e7f5ffa666d0b53
The early return was missing an unlock, as the normal return path has.

Spotted by Matias De lellis <mati86dl@gmail.com>

https://bugzilla.gnome.org/show_bug.cgi?id=752946

pwithnall/totem-pl-parser,pwithnall/totem-pl-parser