Ability to skip when both decks are playing on auto dj

[crisclacerda]

This PR fixes this https://bugs.launchpad.net/mixxx/+bug/1399974?comments=all

Now when 2 decks are playing it assumes the user wants to remove the next track on the auto dj playlist.

[daschuer]

Thank you for your first PR.

Unfortunately a commit hook on Travis fails:

Trim Trailing Whitespace.................................................Failed

You may also install the commit hooks locally if you like:
https://github.com/mixxxdj/mixxx/blob/master/.pre-commit-config.yaml
Unfortunately this was only tested on Linux, so you may discover issue on MacOs.

Unfortunately another test fails as well:

206 - EngineMicrophoneTest.TestInputMatchesOutput (Child aborted) 

Likely a false positive, so we can ignore it here. I sorry about that. Our CI is not that reliably. We need to work on it but that is another topic.

[daschuer]

The code looks good to me (LGTM). Thank you.

If you have a Launchpad account you can assign the bug to yourself.

Before merge, we need your permission.
Please sign:
https://docs.google.com/a/mixxx.org/spreadsheet/viewform?formkey=dEpYN2NkVEFnWWQzbkFfM0ZYYUZ5X2c6MQ

and comment here when done.

[Holzhaus]

@daschuer The patch looks pretty small. Do you think it makes sense to backport this fix for 2.2.4?

[daschuer]

Yes probably.
@

[daschuer]

Sorry the close and comment button strikes me again.
@crisclacerda please rebase your branch to 2.2
And forth push it. This will update this PR.
Than we can change the target branch to 2.2

[Holzhaus]

In case you don't know how to rebase: https://mixxx.org/wiki/doku.php/using_git#targeting_another_base_branch

[uklotzde]

git rebase --onto 2.2 49372742c5637a71b833d84695c95aaa8b775608^

[crisclacerda]

Made changes, commented on launchpad post and signed document.

[crisclacerda]

Hm, it failed again to build on CI. Now it looks like it's trying to use python 3 when building on mac OS.
Sorry about that, I am not familiar with these systems.

File "/Users/travis/build/mixxxdj/mixxx/build/osx/OSConsX.py", line 36
    print s,
          ^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(s, end=" ")?

[daschuer]

Here is the tailing white space error, Travis complains about.

[daschuer]

I think in this case we can ignore most of the CI build issues. This is all a bit legacy.
I am just building locally and if it works successful we can merge.

[uklotzde]

The 2.2 CI builds are broken depending on the platform and won't be fixed. These are known issues. We need to abandon the 2.2 branch with a final release asap.

[uklotzde]

Please add a descriptive line with a reference to the bug to the CHANGELOG

[daschuer]

LGTM Thank you.

[crisclacerda]

Nice, thanks for guiding me through my first PR and sorry for any inconvenience, hopefully, next ones will be more smooth =)

[daschuer]

To be honest, this was quite smooth, every complains where of type tap doors.
I am sorry for that. Carry on. :-)