[Schema Inaccuracy] "Merge a pull request", commit_message body parameter

[gsnedders]

Schema Inaccuracy

c.f. https://docs.github.com/en/rest/pulls/pulls?apiVersion=2022-11-28#merge-a-pull-request

https://github.com/github/rest-api-description/blob/50bf833eb2c1288fb78419d9e4d359fda3c3ccbe/descriptions/api.github.com/api.github.com.yaml#L36643-L36645

This documents:

commit_message string
Extra detail to append to automatic commit message.

However, it seems like, at least for the "squash" merge method, it replaces the commit_message, rather than appending it.

Expected

I hoped it would, like the behaviour of "Squash & Merge" in the Web UI, allow me to specify the entire commit message.

I fear it would, as documented, keep the auto-generated commit message and append a string there.

Reproduction Steps

gsnedders@gsnedders-lonnie tmp-symmetrical-meme % gh api \             
  --method PUT \
  -H "Accept: application/vnd.github+json" \
  -H "X-GitHub-Api-Version: 2022-11-28" \
  /repos/gsnedders/tmp-symmetrical-meme/pulls/2/merge \
   -f "commit_title=Fix README" -f "commit_message=Will this be appended or replace the old body?" -f "merge_method=squash"

This merge entirely replaced the old body, rather than appended it as documented.

[shiftkey]

👋 Thanks for the feedback. I've reached out to the team that handles this API to confirm this is the right change, and we'll follow up if there are any additional questions.