Pie Chart Gadget Cannot Parse JQL with Nested Filter and WAS operator

Problem

The Pie Chart gadget results in a 500 error when the following conditions are met:

• JIRA Pie Chart Gadget
• Pie Chart users a Filter that references a different filter
• The JQL also contains the "WAS" operator
  • All 3 of the above requirements must be met to reproduce the bug.

Steps to Reproduce

• Create a filter referencing another filter and the WAS operator
  • Example:

    filter = "testfilter" and assignee was "admin"
    

• Save filter
• Navigate to the dashboard and add a Pie Chart gadget
• Use the filter we just created and save

Expected Results

No problems, pie chart will load just fine.

Actual Result

A 500 error showing something like this:

Looks like we can't show you the content of this gadget due to its configuration.
filterId should not be null!
500
com.atlassian.jira.util.dbc.Assertions$NullArgumentException: filterId should not be null!

Other notes

The problem is specific to the Pie Chart Gadget

• Other gadgets work just fine with the filter
• Using the Pie Chart report via Projects