Cannot create export files larger than 4G

Due to limitations of the original ZIP file format, and the TrueZIP library used to generate ZIP files, it is not possible to export a Bamboo instance when the resulting ZIP file, or the original size of any of its components, are larger than 4G.

We should adopt an export file format and that does not have this constraint. ZIP64? .tar.gz? .tar.bz?

We will need to maintain support for importing ZIP exports produced by older versions of Bamboo.