cubicweb-vcsfile #1749091 buggy set_at_revision w/ merge nodes [resolved]

prioritynormal
typebug
done in1.8.3
load0.500
load left0.000
closed by#7d3efe9dcfed fix set_at_parent_revision vs merge nodes: should only get back at_revision from 'main' revision. Closes #1749091