It does seem in retrospect that it was a mistake to not have compiletime be more specific, e.g. cacher_compile_time + update_compile_time.

There have been lots of times I've done testing in EC2 on older instances and have had failures on bootstrap because the apt cache was out of date and pointed to old versions of a package. I would have wanted a compile time update, but the cacher business would have been unnecessary (or potentially a problem?).

I'm not in love with more attributes, but I don't see another way to do this.