Unknown tag attribute: rel. Issue detected while parsing form o_pagination on page default

[rwetzlmayr]

Expected behaviour

Smooth article rendering

Actual behaviour

Rendering a single article shows this trace on top of the page:

Tag error: <txp:link_to_prev rel="next"><txp:if_yield name="title"><txp:title /></txp:if_yield><span class="a_icon a_icon--large a_icon--arrowcirc">&#10132;</span></txp:link_to_prev> ->  Textpattern Notice: Unknown tag attribute: rel Issue detected while parsing form o_pagination on page default

Tag error: <txp:link_to_next rel="prev"><span class="a_icon a_icon--large a_icon--arrowcirc-left">&#10132;</span><txp:if_yield name="title"><txp:title /></txp:if_yield></txp:link_to_next> ->  Textpattern Notice: Unknown tag attribute: rel Issue detected while parsing form o_pagination on page default

Steps to reproduce

1. Run Textpattern 4.9.0-dev.
2. Install all-grid theme for the default section.
3. Visit a single article on the public site.