Fix a possible memory leak inside Repository#exists?.
Fix a possible memory leak inside Repository#exists?.

tpickett66/rugged,tpickett66/rugged,saraid/rugged,libgit2/rugged,Acidburn0zzz/rugged,libgit2/rugged,Acidburn0zzz/rugged,Acidburn0zzz/rugged,tpickett66/rugged,saraid/rugged,libgit2/rugged,saraid/rugged