Merge commit not included in notification email

For merge commits the actual merge commit is not included in the generated email, and the From: used for the email is not reflecting the author of the merge commit.

For example, here's a merge commit for a bulk integration from mainline to portola:

https://github.com/openjdk/portola/commit/2331e1b2d815e25eaa6be3a8d8a2f3e26aa32e86

And here is the generated email:

https://mail.openjdk.java.net/pipermail/portola-dev/2020-July/000449.html

The merge commit has me as the author, but the email does not include that merge and appears to be using the most recent commit merged in from mainline as source for the information used in the email header.