don't include commits that belong to a pull request

[lalitkapoor]

this applies when in commits mode (--data commits).

Instead, include the first (non blank) line of the commit body. The commit will have a message that matches "Merge pull request #"...

[lalitkapoor]

I could fetch the commits that belong to a pull request via the API, but since I've got the commits I think I should be able to reconstruct the DAG and determine which commits to ignore.