How to create missing subversion tmp files

After importing a project into my IDE, subversion started giving this error:

svn: Your .svn/tmp directory may be missing or corrupt; run 'svn cleanup' and try again

Unfortunately, 'svn cleanup' was unable to fix this problem.

I was able to create all of the required .svn temporary directories with the following command:

find . -iname '.svn' -exec mkdir {}/tmp \;