FIXME? Inflater docs say:  'it is also necessary to provide an extra
\"dummy\" byte as input. This is required by the ZLIB native
library in order to support certain optimizations.'  However,
this does not appear to be true, and in any case, it's not
entirely clear where the byte should go or what its value
should be.  Perhaps it suffices to have some deflated bytes
in the first buffer load?  (But how else would one do it?)