GitHub network graph representing wrong first parent after merge

Question

I\'ve found a discrepancy between the GitHub network graph and the git log.

Compare the network graph of my GitHub repository called niagara

Answer 1

As far as I can tell, you're right: something is off. In particular, that curved green arrow seems to indicate that commit 6d3ca43 is "twice" a parent of commit a731e72, which makes no sense.

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As far as I know, there is no way, in Git, for a commit to have two parents that are actually one and the same. Even if you're in the following situation (and your working directory is clean),

o -- o [master=HEAD,develop]

running

git merge --no-ff develop

is a no-op: the output of that command is simply

Already up-to-date.

Conclusion: my feeling is that it is a bug on GitHub's side...

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Update: I contacted GitHub's support about this and they got back to me. Read below.

Thank you for calling our attention to that network graph -- I agree that looks confusing. I've opened an internal issue to let our team know about this, and we'll get back to you as soon as we have more information.