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Changes:

• AutoSuggestAPITest skipped a test on travis-ci since the cause of the failure was unknown. Found the cause to be an error in tracking in the associated fixture. The fixture used bulk tracking, which unsets the user agent after queuing a request (see https://github.com/piwik/piwik-php-tracker/blob/master/PiwikTracker.php#L1534). Re-setting the user agent in the fixture fixed the tests (verified the new output files manually).
• In CliMulti, ignore defunct processes (aka, zombie processes) in ps output. In certain environments, (such as the php:5.6-fpm docker container), exiting pre-maturely in a RequestCommand execution can cause the PHP process to become a zombie, so it remains in ps output. This caused CliMultiTest to hang indefinitely.
• Set the URL to two requests that were missing it in the ThreeVisitsWithCustomEvents fixture. The default URL depends on the $_SERVER['HTTP_HOST'] value, which during tests depends on the [tests] http_host INI config. Which means it could be different based on a dev's local environment.
• OneVisitorTwoVisitsTest was re-used in another test (DuplicateActionsTest). This caused PHPUnit to skip the test when both tests were run together (eg, on travis-ci), since PHPUnit doesn't use the composer autoloader.
• In the SomeVisitsCustomVariablesCampaignsNotHeuristics fixture, encode the attribution date time. The Piwik tracker doesn't URL encode this value, so the space in the date time value is sent raw. In my environment this caused the request to fail before even getting to Piwik. This might be something that needs to be fixed in a BC way in the PHP tracker too.

Should fix #11746