If an old version of a package is left around in a 'work'
	directory, and pksgrc is updated, its possible to get into
	a confused state whereby the old version is installed but
	registered as the new.

	One thought would be to echo the version into the 'work/.xxxx_done'
	files, another might be to create a 'work/.versions' file which
	contains the output for something like 'md5 Makefile files/[a-z]*
	pkg/P*'.

	What do people think?