I'm not convinced that the zeros() method is needed. Zero-initialized sequences can be created via sequence repetition. Sorry, but arguments against this sound like "we made bad design decision in the past, let repeat it with new name" to me.

In any case if you want to write a code for different Python versions you should use sequence repetition.

Here is a patch that replaces all creations of zero-initialized bytes and bytearray objects in the stdlib and tests with repetitions. All tests (except test_bytes of course) are passed on Linux if disallow an int argument in bytes and bytearray constructors.