NPE in api when calling getRevision() on a tag directory

eg http://localhost:6060/foo/api/rest/revision?path=tags%2F/tag1/a.txt&rep=zvn&rev=13

The fe-jira plugin (1.2.1) exercises this issue.

[java] java.lang.NullPointerException
[java] at com.cenqua.fisheye.rep.SortedMapFileHistory.getRevision(SortedMapFileHistory.java:87)
[java] at com.cenqua.fisheye.api.ApiImplementation.parseRevisionRequest(ApiImplementation.java:598)
[java] at com.cenqua.fisheye.api.ApiImplementation.doGetRevision(ApiImplementation.java:561)
[java] at com.cenqua.fisheye.api.ApiImplementation.handleCommand(ApiImplementation.java:186)
[java] at com.cenqua.fisheye.api.ApiImplementation.handle(ApiImplementation.java:178)
[java] at com.cenqua.fisheye.api.BaseApiServlet.doPost(BaseApiServlet.java:25)
[java] at com.cenqua.fisheye.api.BaseApiServlet.doGet(BaseApiServlet.java:16)