So I think what is happening is that the network interface is coming up before squid has installed a handler for SIGHUP.
*tons* of stuff happens between squid starting, and squid installing its signal handlers. I haven't gone through all of the code but I'm betting at least one or two stall on not having a network yet. It would seem that squid should probably ignore SIGHUP almost immediately on startup to avoid this issue.
I've pushed up a branch that makes that change, and I'll put up packages in a PPA soon that affected users can test.
So I think what is happening is that the network interface is coming up before squid has installed a handler for SIGHUP.
*tons* of stuff happens between squid starting, and squid installing its signal handlers. I haven't gone through all of the code but I'm betting at least one or two stall on not having a network yet. It would seem that squid should probably ignore SIGHUP almost immediately on startup to avoid this issue.
I've pushed up a branch that makes that change, and I'll put up packages in a PPA soon that affected users can test.