Issue Summary

By default, Bamboo should use shell interpreter for YAML, however, this is not the case

Steps to Reproduce

version: 2
......
  tasks:     
     - script: |
        #!/bin/bash
        Hello Bamboo

Expected Result

The interpreter will be chosen based on the shebang line of the script. shell (default)

Actual Results

Interpreter is /bin/sh or cmd.exe

Workaround

Add shell as interpreter value

task:
......
  - script:
     interpreter: shell
     scripts:
     - '#!/bin/bash'
     - 'ls  ${pwd}'