通过不(重复)对备份进行gzip压缩，减少本地磁盘空间需求

[RGJ (Richard - Communiteq)]

@Ed_S

If a subshell were being used, the output of tar could be piped into gzip. But I think in fact some higher level ruby functions may be in use.

cough

discourse/discourse/blob/7b89fdead98606d4f47ceb0a1d240d0f6e5f589e/lib/compression/tar.rb#L13-L21