Revert "Differentiate socket closed from socket error in recv_line."

This reverts commit 2f89eef4b1eb23e6ac5b11ecd1e128eb6429d609.

Conflicts:
	util.c
Revert "Revert "Differentiate socket closed from socket error in recv_line.""

This reverts commit 481cfa617bc1bb14e99f588703171cfc9316584d.
Fail even if there is data in the recv buffer at the appropriate time.