Run this command across the source:
perl -pi.bak -e 's/(20[012][0-9])-20[12][012]/$1-2023/g' `git ls-files`
and remove changes to po{,-docs}/*.po{,t} (these will be regenerated
later when we run 'make dist').
The previous code:
fcntl (fd, F_SETFL, O_NONBLOCK)
was technically incorrect, because it would have reset any
other flags on the file descriptor.
Thanks: Eric Blake