On Fri, Oct 09, 2020 at 01:46:07PM -0400, Derrick Stolee wrote: > > Can you reproduce it if you do > > > > git config core.commitGraph false > > git config fetch.writeCommitGraph true > > ? > > I _can_ repro it in this case! I think there must be something > very interesting going on where the commit-graph is parsed in > _some_ places, but not in others. This is something that I can > really start to dig into. Here's a much more minimal reproduction: git init repo cd repo git commit --allow-empty -m one git rev-parse HEAD | git -c core.commitGraph=false \ commit-graph write --split=no-merge --stdin-commits git rev-parse HEAD | git -c core.commitGraph=false \ commit-graph write --split=no-merge --stdin-commits git commit --allow-empty -m two git rev-parse HEAD | git commit-graph write --split --stdin-commits The final write will die() with the "unexpected duplicate" message. -Peff