Our current default is to create a version-opt string on the format '<timestamp>.<username>.<base dir name>' during configure.

The problem with this is that each time the configure script has change, a reconfigure is triggered. This will create a new version-opt, and hence a new version string. This in turn will trigger a rebuild of hotspot and java.base, and that in turn rebuilds the whole world.

It does not have to be like that. In fact, storing the time stamp of the last configure, rather than the time stamp of the last build is rather silly anyhow.

In a perfect world we could just update the version-opt string and have this resulting in an extremely short rebuild time. Unfortunately, we do not live in a perfect world, and here it makes more sense to drop the timestamp.

Note that this only affects adhoc (developer) builds.