apparent bug in gzip section of runtests.jl

[bdklahn]

It looks like the BufferStream, http_buffio, is never used (tested) in the gzip testing section.

SimpleBufferStream.jl/test/runtests.jl

Lines 240 to 241 in b1ffb92

	# Ensure that streaming HTTP -> BufferStream -> Gzip works
	http_buffio = BufferStream()

So it looks like that section might be merely testing whether and http stream can work though a gzip process pipe.