Upstream libcURL 7.29.0 has a regression socket leak in some usages. Specifically, at least the usage in net-misc/bfgminer for failed HTTP pools never disconnects the socket, and eventually runs out of file descriptors. The bug was introduced after 7.28.1, and fixed in git commit e7c56a8406d0d751b8afc1daf2dcbb67c763c465
its off the tree.