Fix specs when running on JRuby.

[lucasallan]

There is a difference in how JRuby and MRI sort_by algorithm works when sorting elements with the same weight. More info: jruby/jruby#3004

Calling #sort! before #sort_by in JRuby appears to make it work just like MRI does.

[runlevel5]

@lucasallan thanks for the PR. I could see JRuby 9k build still fail. Does this PR address that issue or different one?

[lucasallan]

That failed spec doesn't seem related to my changes. I ran the specs several times in my local environment with JRuby 9k (jruby 9.0.1.0) and it always pass. I also noticed that you're running on JRuby 9.0.0.0.pre1 - this might be the issue.

➜  controller git:(master) ruby -v
jruby 9.0.1.0 (2.2.2) 2015-09-02 583f336 Java HotSpot(TM) 64-Bit Server VM 25.60-b23 on 1.8.0_60-b27 +jit [darwin-x86_64]
➜  controller git:(master) rake test
Run options: --seed 29639

# Running:

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Finished in 6.945280s, 365.4280 runs/s, 832.9398 assertions/s.

2538 runs, 5785 assertions, 0 failures, 0 errors, 2 skips

You have skipped tests. Run with --verbose for details.
➜  controller git:(master) 

[lucasallan]

@JONESLEE85 I added the latest version of jruby 9.0.1.0 to the .travis.yml and all the specs are passing.

[runlevel5]

@lucasallan should we bump our requirement to min 9.0.1.0?

[runlevel5]

cc @jodosha @AlfonsoUceda for 1 more 👍

[lucasallan]

Yes, I think so - this is the stable release version of JRuby 9k.

[jodosha]

@lucasallan Thanks, I've merged it! ✨

[brennovich]

Yay! Great job :)

We're almost there 💃