Re musl changing their behavior, see https://www.openwall.com/lists/musl/2018/09/07/1 and the resulting thread.

In addition to the old kernel version issue, two other issues were raised:
1. EINTR makes programming mistakes more likely, as people won't think to handle it. I don't give much weight to this point.
2. Most of the time, counting on receiving an EINTR results in race conditions. Our code seems to be affected by this too. Even on glibc, a signal at just the "right" time could result in it not being interrupted. This is why I think moving to an eventfd or something would be better, since we could then use pselect/ppoll/etc. to avoid the signal blocking race.