DataStream..use(function* {}) times out during test.

[MichalCz]

Basics
The issue affects DataStream..use(function* {})

Describe the bug
The current test times out.

To Reproduce
Steps to reproduce the behavior:

1. Checkout this repo.
2. npm install
3. npm test
4. See error:

✗ data-stream/test_use/generator
   ✓ ok(Must return a stream synchonously)
   ✓ ok(Must not be called and executed synchronously)
   ✓ equal(Must be called with self as first argument)
   ✓ equal(Additional arguments must be passed)
   ✗ fail(test timed out after 10000ms)
   ! test timed out after 10000ms

Expected behavior
Should not time out.

Test case
nodeunit-tape -t node_modules/scramjet_core/test/v1/data-stream.js

System:

• OS: Ubuntu Server 18.04
• Node version: v8, works on v10/latest.
• Scramjet Version: 4.20

Additional context
It is possible that PromiseTransformStream.whenRead times out if reading beyond stream end.

[MichalCz]

Bad behavior of whenRead confirmed, additionally more items were read by the first item.

To be fixed in 4.20 patch.