Describe the bug
I'm trying to upgrade blt to the latest version. I'm still stuck with 13.5.1 due to the changes in drupal-environment-detector. I'm using acquia/blt-travis to run tests on travis-ci. After switching to the master branch, travis-ci seems to work correctly with the latest blt. However, I now get issues with acquia-pipelines.
Expected behavior
Test should run successfully on both travis-ci and acquia-pipelines with latest BLT version.
Detailed error output
`[info] Drush bootstrap phase: bootstrapDrupalConfiguration()
TypeError: Acquia\BltTravis\Blt\Plugin\EnvironmentDetector\TravisDetector::getCiSettingsFile(): Return value must be of type string, none returned in Acquia\BltTravis\Blt\Plugin\EnvironmentDetector\TravisDetector::getCiSettingsFile() (line 16 of /mnt/tmp/local.prod/source/vendor/acquia/blt-travis/src/Blt/Plugin/EnvironmentDetector/TravisDetector.php).
[warning] Drush command terminated abnormally.
[Acquia\Blt\Robo\Tasks\DrushTask] Exit code 1 Time 0.19s
[error] Failed to install Drupal!
For troubleshooting guidance and support, see https://docs.acquia.com/blt/support/ `