Delete a Test Step returns a javascript error in dialog view and a 400 bad request in the issue view when importing steps in the issue dialog

Short Description: Delete a Test Step returns a javascript error in dialog view and a 400 bad request in the issue view when importing steps in the issue dialog.

Steps to Reproduce:
1 - Create a Manual Test issue.
2 - Click to open in dialog.
3 - Import steps from a csv, for example. It happens for all the imports.
4 - Now, delete test step.

Actual Results: A javascript error is displayed.
Expected Results: Steps should be deleted.

5 - Now, click in the "Save" button.
6 - Try to delete the steps in the issue view.

Actual Results: The first test step is deleted but all others return a 400 bad request.
Expected Results: The test step should be deleted.