Avoids:

- Relying on github’s services
- Fetching a new (malicious) version, automatically, without any “check”

Because if we have a send event to signal the connection sucess + a recv
event to signal something to read on the socket, we need to first finish the
connect process before reading the available data. That’s what we do now.

I think it was a UB

fix #3157

ref #3152

The unit file Type=, as well as the executable path should now be correct
with a simple “make install”, whatever the install prefix and the DESTDIR
values are.

ref #3152

fix #3151