Spawns {cmd} in a new pseudo-terminal session connected to the current buffer. {cmd} is the same as the one passed to |jobstart()|. This function fails if the current buffer is modified (all buffer contents are destroyed). The {opts} dict is similar to the one passed to |jobstart()|, but the pty, width, height, and TERM fields are ignored: height/width are taken from the current window and $TERM is set to "xterm-256color". Returns the same values as |jobstart()|. See |terminal| for more information.