Fix double subscription bug

[haritowa]

Hello, my team recently start a transition to RxSwfit 4.x, as far as I can see, RxAutomaton does not have rxswift 4 branch and HEAD dependency is ~> 4.0.0. After manual transition(plain dependency bump) we have observed strange behavior: RxAutomaton subscribes to each cold edge twice.

The bug was caused by updated .share operator, which now have two parameters(replay elements count and strategy) with strange default values: by default new share behavior differs from the old one.

My PR contains three commits:

• dependency bump
• test case, that exposes a bug(5b2431a)
• fix (44703bf)

So far, this is the only critical issue, caused by the transition to RxSwift 4.x, maybe we should perform needed tests/warning fixes and bump dependency version?

[haritowa]

You can run tests using 5b2431a version and observe the bug yourself

[inamiy]

@haritowa
Thanks for catch!
Fixes look good, except f81ad93 having wrong configuration and not really needed for this pull request.

Can you revert f81ad93 ?

P.S. Discussion of .share's default scope can be found here: ReactiveX/RxSwift#1527

[haritowa]

If I'll revert dependency bump - code will not compile, is it ok?)

[inamiy]

I don't think reverting f81ad93 will break the code.
At least, s.dependency "RxSwift", "~> 5.0" is currently not available as in f81ad93.

[haritowa]

Ooops, I thought ~> 5.0 means 4.0 ..< 5.0, ok, I'll drop that commit

[inamiy]

Thanks for contribution!