[tz] Version in zoneinfo files?

[Paul Eggert]

Paul G wrote:
> If not, I would like to suggest that a VERSION or METADATA file be added
> to the zoneinfo output.

Although there is a version number in those files, it's not what you're looking 
for: it's the version number of the zic format (a number that changes only very 
slowly), not the tzdata version number. There's no provision in the current zic 
format for storing an arbitrary tzdata version number like '2015g'. Perhaps we 
could add one, but there would be a downside: people might take strings like 
'2015g' too seriously, and assume that two files from different sources labeled 
'2015g' would be identical (an assumption that would not be true). This downside 
has made me reluctant to change the zic format in this area.