I've got some common test data that I download for multiple packages
using rosbuild_download_test_data(). I'd like to put it in a single
shared directory so I only have to download it once for all the tests
in the stack.

My first attempt was to download it to the tests subdirectory of a
common package that others depend on, then reference it there, but
there seem to be race conditions in the build systems causing that not
to work reliably for the other packages.

 Is there a recommended place to put things like that? Would
/tmp/<stack_name> work? Or should I just download a separate copy for
each package?

-- 
 joq