[fix] improved version parsing check again (in case parsing fail of gives empty result) and check if @upstream is empty in resolt (as a manual modification could render the version unusuable)
[fix] do version parsing better and raise an error if the recomposed version does does not match the provided one
[fix] ensure input versions are all strings (which will treat nil as an empty string, which is fine)
[evol] added licence information
Initial code
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