GeezerVison

This is very minor so I did not create an issue on bugs.python.org.

I am working on a gzip-compatible library and used the tests from cpython to ensure that it was indeed compatible. I found these minor oversights when testing the library.

1. a decompressor is finished when it reaches eof. Not when it has no unconsumed tail left. The last case merely meaning it was able to consume all input, and not meaning it is finished.
2. A gzip header only stores the basename of the file. The expected name in the test used the full path. Presumably because it was a relative path with no subdirectories.

I also found test cases testing a Wbits of 32+15. Wbits sizes over 31 are undocumented in both the python and zlib documentation. Can anyone explain to me what these test cases are for, and why it is a hard requirement that these undocumented assumptions may never be broken by future python releases? I found it in the docs. It autodetects gzip or zlib style compression. That is quite a neat feature!