Docs build problems

[Kim Haase]

As you all may have noticed, the Derby docs builds have been failing 
lately. All the builds from 148 through 153 have failed except for 152. 
For the failed builds, there seems to be no log file -- when I try to 
access 
https://builds.apache.org/job/Derby-docs/153/artifact/antoutput.log.gz 
as advised by the console log, there is nothing there.

Our build expert, Kristian Waagan, is out on leave until January. Has 
anyone else enough knowledge to figure out the build problems? I'm 
afraid I do not.

Thanks very much,

Kim