SOAP progressWorkflowAction to resolved or closed gives error

Same test works fine against 3.13.3. Fails on 3.13.4.

Remote error: com.atlassian.jira.rpc.exception.RemoteValidationException: Fields not valid for workflow action Resolve Issue: 
Errors: {assignee=Issues must be assigned.}

Here is one way to reproduce this:

1. Download jira cli client 1.1 from http://confluence.atlassian.com/display/JIRAEXT/JIRA+Command+Line+Interface
2. Run the following against an appropriate issue

   ./jira.sh --server http://localhost:8201 --user automation --password automation --action progressIssue --issue TESTCASE-3 --step "resolve issue" --resolution fixed