Spawns {cmd} in a new pseudo-terminal session connected to the current (unmodified) buffer. Parameters and behavior are the same as |jobstart()| except "pty", "width", "height", and "TERM" are ignored: "height" and "width" are taken from the current window. Returns the same values as |jobstart()|. Terminal environment is initialized as in ||jobstart-env|, except $TERM is set to "xterm-256color". Full behavior is described in |terminal|.