For me leveldb looks like Version 1.2 but this is from 2011-05-16 as mentioned here: https://github.com/signatumd/source/blob/master/src/leveldb/NEWS . This is pretty near to 6 years. But it also says "Fixes for larger databases (tested up to one billion 100-byte entries, i.e., ~100GB)" . I will investigate further.
It is confusing, and I can see how some people might have looked at the code and thought it was 6 years old.
The actual version number in db.h is 1.17, as well as the version number in the makefile.