[Python-Dev] test_zlib.py suggestion

[Michael]

I have a build_bot running (yeah me!), and was surprised to see 
test_zlib fail on AIX.

There is not an issue with test_zlib, but I do have a suggestion.

I was getting an error with test_flushes(). On python2-2.7.15 the test 
passes and in python3-3.8 (and earlier I expect) the test fails. The 
difference is the addition of the two modes 'Z_PARTIAL_FLUSH' and 'Z_BLOCK'

sync_opt = ['Z_NO_FLUSH', 'Z_SYNC_FLUSH', 'Z_FULL_FLUSH',
             'Z_PARTIAL_FLUSH', 'Z_BLOCK']

On default AIX installs zlib is, sadly, still at version 1.2.3 and 
Z_BLOCK was 'improved' in version 1.2.5. And it fails on Z_BLOCK.

My suggestion is to enhance the test_library_version() so that it 
verifies that the minor (or smaller?) number is at least '5'

When I static link python with zlib-1.2.11 then the test_zlib passes all 
sub-tests.

Again, not a python bug - but a suggestion for improving what is tested.

I can open an issue, and with a bit of assistance/interest from others 
I'll even do a PR.

Michael