Issue Summary

JQL query when used as below : 

labels != xyz 

Does not return the issue that has no labels in it.

Steps to Reproduce

1. Create a JQL query in advanced search as below : 
   labels != <labelname> 
2. Search and you will see that the issues that do not have empty values in labels field will not be returned.

Expected Results

expected to return all the issues which does not have labels as xyz (including those who have labels field empty) to be returned.

Actual Results

The issues that has another value in labels field except for the searched value will be returned.

Workaround

workaround is to use labels = null to retrieve the results.