fix implication that op is updated when -1 is returned.
fix implication that op is updated when -1 is returned.


svn path=/trunk/ogg/; revision=15906

ksophocleous/ogg,ShiftMediaProject/ogg,emscripten-ports/Ogg,eidy/libogg,brion/ogg,nicolaichuk/ogg,brion/ogg,nicolaichuk/ogg,youfearm3/ogg,emscripten-ports/Ogg,ShiftMediaProject/ogg,mwgoldsmith/ogg,ksophocleous/ogg,youfearm3/ogg,xiph/ogg,xiph/ogg,eidy/libogg,felipebetancur/ogg,mwgoldsmith/ogg,felipebetancur/ogg