For modules, we want to record the module name[s] used, if and only if it was symbolic, in BitKeeper/log/MODULES. The reason for this is so that subsequent pulls need to use this file, unioned with any components not implied by the file, so that they get any new components, i.e., if a module "tools" started with gcc, someone clones, the parent adds gdb, the child pulls, then the child should get a new gdb repo.

This opens up a few questions:

We need test cases for: