[cvsnt] BUG: Update with non-existing tag deletes sandbox files

[Luigi D. Sandon]

> 2) Stop the operation and show a warning?
> Why?

Because the user then *knows* it was asking for a non-existent tag. If 
someone not aware of the "feature" slightly misspells a tag and gets an 
empty repository, what do you think he would think while scratching his head 
trying to guess why he got an empty sandbox? And what happens if someone 
branches from a non-existing tag? No error and where does the branch start 
from? Or the behaviour are different?

When a database application returns no record do you just show an empty 
window, or inform youir user that his search returned no record?

-- 
Luigi D. Sandon