Content of job scripts should not be overwritten on change of script type

Current Situation

• When a user selects the script type in the Job Properties tab of the Configuration View  from "Shell" to "JavaScript", then the user's shell script is overwritten. Even after switching back to the "Shell" script type it displays the JavaScript function only.

How to reproduce

• Create a job in a workflow
• Write a shell script for the job.
• Change the script type of the job to "JavaScript".
• This will add a basic JavaScript function to the job script.
• Now change the script type to "Shell" again.
• The JavaScript function is still available and the shell script created is removed

Desired Behavior

• The contents of the shell script should not be cleared when changing the script type.