The review bot flagged a real hazard in the owner-evidence bookkeeping: a
mention whose `references` edge is already in the graph returned early, so
the document never recorded that it cites the target. A later bare method
mention in the same document then lost its owner and was dropped.
`_add` now records the cited target before it decides whether the edge has
to be written, so the evidence survives an edge that is already there.
The pipeline cannot reach that state today (the resolver is handed a fresh
edge list, and the incremental context only carries contains/method/
inherits/imports edges), so this is hardening rather than a fix for a
reachable failure. The regression test drives the resolver directly with a
pre-existing class edge.
(cherry picked from commit 37efe877cf)
nothariharan
a287c0795a