YAML multiline strings

I guess I found the cause: The multiline string is rendered correctly only if all the lines start at the same column than the first one:

Wrong

after_success:
  - >
    run_test.sh
      arg
      --flag-1
      --flag-2

Good

after_success:
  - >
    run_test.sh
    arg
    --flag-1
    --flag-2

I don’t know if this is part of the YAML spec. In other projects I used several levels of indentation without problems in multiline strings.