The document linked from the URL apparently contains an incomplete Deflate stream. Nonetheless, the document displays exactly as in Adobe Reader, if we don't throw by requesting more input but instead be done with it as in http://code.google.com/p/sumatrapdf/source/detail?r=1302 (this might still throw later on, if the stream indeed was too incomplete).
Turns out that this issue is also solved by calling inflate with flush=Z_FINISH at the end of the stream (which per zlib's documentation is even required): http://code.google.com/p/sumatrapdf/source/detail?r=1304