GZIP "OS" header flag hard-coded to 0 instead of 255 (RFC 1952 non-compliance)

Summary

GZIPOutputStream does not write out the correct default value for the GZIP header OS field.

Problem

GZIPOutputStream currently sets the OS field in the GZIP header to 0 (which means FAT filesystem) which does not match the default value specified in section 2.3.1.2 of the GZIP file format specification version 4.3 (RFC 1952)

Solution

Set the OS header field to 255, the default value, as defined in section 2.3.1.2 of the GZIP file format specification version 4.3 (RFC 1952)

Specification

The default value for the OS header field is specified in section 2.3.1.2 of the GZIP file format specification version 4.3 (RFC 1952).