Draft pull request assigned before marked ready for review

[andreoss]

Github provides "draft pull request" feature

• Zerocrat assigns such PRs before they are marked ready, which is inconsistent with the feature.
• Zerocrat should assign a reviewer, after the PR has been marked ready by its author.

Described behavior can be seen here https://github.com/llorllale/cactoos-matchers/pull/154

[0crat]

@g4s8/z please, pay attention to this issue

[0crat]

@andreoss/z this project will fix the problem faster if you donate a few dollars to it; just click here and pay via Stripe, it's very fast, convenient and appreciated; thanks a lot!

[andreoss]

Blocked by https://github.com/jcabi/jcabi-github/pull/1527