JQL history queries using resolution field does not translate "Unresolved" to "EMPTY"

Steps to Replicate

Access the following two links (two queries on JAC):

• project = JIRA AND resolution WAS Unresolved AFTER -7d, and;
• project = JIRA AND resolution WAS EMPTY AFTER -7d.

Current Behavior

In JIRA 6.2, the "Unresolved" synonym for "EMPTY" with the resolution field is not working as expected (this problem only occurs with the historical operators, i.e. WAS, WAS NOT or CHANGED)

Expected Behavior

The JQL queries should return the same results.