Wolfgang: Unfortunately, I think that block of changes is largely unavoidable. The write() method should not have changed in reality, but all the init and read methods around it have been split into two classes, and the diff has decided to compare the old GzipFile methods to the new _DecompressReader methods. If you like I could try preparing a pseudo diff files that forces it to compare old GzipFile to new GzipFile to highlight the changes there.

Nikolaus: I will try to split my buffer_size parameter changes out and post them in a separate issue that can be enhanced further.