vsdg: add check for root region for jive_region_get_anchor_node
vsdg: add check for root region for jive_region_get_anchor_node

Signed-off-by: Helge Bahmann <c5618920f622561f9c0ec5c42219c4c08180149f@chaoticmind.net>

phate/jive,phate/jive,phate/jive