merge graphs offsets each input's own communities into a shared id
space so they do not fuse (number 3014), but that per source
partition has no relation to the previous MERGED clustering a labels
sidecar was built against. A later cluster only run's label reuse
remap read merge graphs' output as though its community field were
that previous clustering, and silently mismatched almost every
community since it was actually per source ids.
Add a previous flag that reads a prior merged graph.json and restores
its real community value onto each node that survives the merge, by
node id, before the per source offset is ever written out. A node
with no match (new since the previous merge) gets no community rather
than keeping an unrelated per source offset, since an invented value
is worse than none here. The per source partition stays available
regardless, in local community.
Fixes#3858.
(cherry picked from commit 60e153176c)
ayushcodes10
9ec7df04d8