Log exception when parsing .travis.yml fails.
Log exception when parsing .travis.yml fails.

The stack trace has little value in the logs, as the error is
handled gracefully already.

GistIcon/travis-core,travis-ci/travis-core,GistIcon/travis-core,Tiger66639/travis-core,travis-ci/travis-core,Tiger66639/travis-core,developerfm/travis-core,Tiger66639/travis-core,jantman/travis-core,developerfm/travis-core,kidaa/travis-core,kidaa/travis-core,final-ci/travis-core,kidaa/travis-core,travis-ci/travis-core,jantman/travis-core,final-ci/travis-core,GistIcon/travis-core,final-ci/travis-core,developerfm/travis-core