Fix error on 0.6

Author: Keno

src/query.jl

@@ -308,8 +308,10 @@ Base.read(s::Stream) = read(stream(s))
 Base.read(s::Stream, nb) = read(stream(s), nb)
 Base.flush(s::Stream) = flush(stream(s))
 # 0.4 compat
-Base.readbytes(s::Stream) = read(stream(s))
-Base.readbytes(s::Stream, nb) = read(stream(s), nb)
+if isdefined(Base, :readbytes)
+    Base.readbytes(s::Stream) = read(stream(s))
+    Base.readbytes(s::Stream, nb) = read(stream(s), nb)
+end
 
 Base.isreadonly(s::Stream) = isreadonly(stream(s))
 Base.isopen(s::Stream) = isopen(stream(s))