Setting empty value on Update Issue custom field postfunction leads to Transition falied error.

Issue Summary

Using the post function "Update Issue custom field" to clear a field by setting the value to empty for a Select List (Multiple choices) field leads to "Internal server error". The transition fails.

Steps to Reproduce

1. Have a Select list (Multiple choices) field in your screen, set some value to it.
2. Create a post function on a transition to clear this field by option for "Update Issue custom field" and leave the Value to be set to empty.
3. The post function then suggests that the value of this field will be "Cleared".

Expected Results

It should clear the field.

Actual Results

Transition fails with "Internal server error".

Workaround

Instead use the "Clear field value" post function which clears this field.