XDG_STATE_HOME= (or XDG_RUNTIME_DIR, XDG_CONFIG_HOME, XDG_DATA_HOME, HOME) set
to an empty string resolved to a relative 'signaltty' directory under the
process cwd. The XDG Base Directory spec says an empty value means unset.

Co-authored-by: Lucenx9 <185146821+Lucenx9@users.noreply.github.com>