Fix IndexSet/NSIndexSet range merging

[zayass]

Fixes wrong IndexSet range merging. Currently, all range extension collapse this range with next.

Bug introduced here fa68db0#diff-e7f44555b2cc650b187ee9d2cb0e9132R596

Affects 4.0, 4.1 and master

[spevans]

@swift-ci please test

[parkera]

Do these tests pass for IndexSet on Darwin? The implementations are similar I think.

[zayass]

@parkera yes it passes on Darwin
See this diff fa68db0#diff-e7f44555b2cc650b187ee9d2cb0e9132R596

It looks like a typo/copypaste error

Overlapping detects as nextRange.location + nextRange.length >= nextRange.location which alway true

[parkera]

Great, thanks for checking.

[zayass]

@parkera Is it possible to merge this to 4.1 as well?

Looks like build broken by swift tests and foundation not even started to build.

[parkera]

Yah, we can take this on the swift-4.1-branch. Let's try the build again and see if we can get it to pass first though.

[parkera]

@swift-ci please test

[zayass]

Same result. Looks like swift master unstable today. So I will open another pr to 4.1

[zayass]

Hi, @parkera do you know whats going on with Jenkins build?

BTW I checked this tests on older platforms and it also has broken in 3.0 and 3.1 but in little bit different way

[alblue]

@swift-ci please test

[zayass]

Hi @parkera is it ok to merge? Or I should do something more?

[parkera]

LGTM, thanks.

[zayass]

@parkera Could you look at this also #1437