dvips and relative paths

Next oddity: dvips stopped finding figure files in a different relative directory:

dvips: Could not find figure file ../figures/lyapunov.ps; continuing

With a hint from this discussion, it looks like the appropriate --work-properly option is dvips -R0 … (although I've no idea why a relative path is considered a security hole, nor why this is now a problem given that I've not updated dvips).