Incorrect intersection result

[svalaskevicius]

Hi,

I was looking to use IDLSet, and was comparing the perf against some stdlib sets, but noticed, that while on 2/3 benchmarks IDLSet was rather faster, on the 3rd one it failed the checksum that both HashSet and BTreeSet agree upon.

Please see this data for the failing example, as well as the snippet of the benchmark: https://gist.github.com/svalaskevicius/33fb27464867838985f5eea4e7f7ac57

Benchmarking set-intersection/random/IDLSet/1000: Warming up for 3.0000 sthread 'main' panicked at 'assertion failed: `(left == right)`
  left: `194240`,
 right: `192246`', core/benches/core_benchmark.rs:146:17

Thanks,
Sarunas