Nuke a now redundant check whether we are running in a default

Nuke a now redundant check whether we are running in a default
vimage.  Regardless whether we are at the top of the vimage tree
or not, the current vimage will have an address of ".".  More
importantly, we can now _really_ start new experiments from within
non-default vimages, i.e. run IMUNES inside IMUNES!

While here, bump our "version" date.
Bug found by:
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