Please find the attached patch which modifies dodoc, doman and prepman to use bzip2 instead of gzip to compress man pages and docs. I'm sure you know bzip2 has a better compression ratio than gzip. The patch works fine with portage-2.0.50-r1.
Created attachment 27700 [details, diff] bzip2.patch: patches dodoc, doman and prepman to use bzip2
*** This bug has been marked as a duplicate of 9870 ***