The changes are minimal and pushed into the git archive. IDN is enabled by default, non-IDN names still continue to work. In case there is some sort of problem the --no-idn option can be used to disable IDN support.
It is quite easy for other programs to enable IDN as well. Whether it all should just work automatically is another question. There is the problem of look-alike characters in the Unicode range which might undermine the certificate system.