svnbootstrapper deletes .svn/format file

In my config.xml I have

<modificationset>
<svn LocalWorkingCopy="${build.dir}/${project.name}/D1" />
<svn LocalWorkingCopy="${build.dir}/${project.name}/D2" />
</modificationset>

for multiple directories that are to be used to detect changes to 
trigger a build (of course). All is working just fine. There is a 
directory that needs to be updated before a build but not used to 
consider if a build is necessary. I added

<bootstrappers>
<svnbootstrapper LocalWorkingCopy="${build.dir}/${project.name}/XX"/>
</bootstrappers>

XX is a working directory checked out of svn which existed before adding 
the bootstrapper.
During the build from ant, I do another svn update on D1,D2, and XX and 
svn indicates XX is no longer a working directory. Looking at the 
XX/.svn directory, the format file has been deleted. If I take out the 
bootstrapper, recheckout XX from svn, and rerun, all is fine.

I turned on -debug and set log4j to debug but I saw no debug output from 
the svnbootstrapper. I assume it is some svnkit problem since I found 
some posts in other groups about missing .svn/format files. I just don't 
know how to resolve this problem. Any suggestions??

Thanks
Bill

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