[setup] Requesting advice: How to code aPackageVersion == theEmptyPackageVersion (i.e. the one containing defaultversion)

[Max Bowsher]

I've coded a patch for colour-coding versions in the setup picker according to
curr/prev/test. I need a way to test whether a packageversion is the null
packageversion (containing defaultversion in data). At the moment I'm kludging
it by testing for a Name of length 0. I'm thinking of adding an is_empty(), or
similarly named function to packageversion, unless someone has a better solution
?

Max.