Travis is having infrastructure problems since it migrated in November 2017. Our OS X and iOS tests hang for days. When the current job hangs, new jobs that enter the queue later hang too because the original job is still waiting.
The subsequent hangs effect Android and Linux, too. Our Travis scripts test Android, Linux, OS X and iOS. A hang effects everything.
We are going to disable Travis OS X and iOS tests until things improve.
Jeffrey Walton