cubicweb-datacat #5706253 DCAT data import does not work [validation pending]

After adding a datafeed source, dataimport does not work, although we see ``success` in web UI. We can find the following error in log:

ReST / HTML errors:System Message: WARNING/2 (&lt;string&gt; , line 1); <em>backlink</em></p>
Inline literal start-string without end-string.
AttributeError: 'DCATFeedParser' object has no attribute 'vreg'
priorityimportant
typebug
done in0.3.1
load left0.000
closed by#1d9ed0ea3493 Fix data import bug.
patchFix data import bug. [rejected]Fix data import bug. [applied]