When I wrote the test I saw that in write mode a '.gz' extension is automatically added to the filename if it has none. However this is stripped again when the name is written to the gzip header. I removed this so that the name attribute always reflects the real filesystem name. The filename property imitates the old behaviour.

I don't think that this should necessarily be backported, at least I don't need it ;-)

Applied in rev. 53772.