Fix poor worst case performance of set intersection#57043

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bors merged 4 commits intorust-lang:masterfrom

Jan 15, 2019

Commits on Dec 21, 2018

Fix poor worst case performance of set intersection (and union, somewhat) on asymmetrically sized sets and extend unit tests slightly beyond that
ssomers
committed

Commits on Jan 9, 2019

Commits on Jan 10, 2019

Merge remote-tracking branch 'upstream/master'
ssomers
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