There is a undocumented way (below) to determine if a branch is configured to auto-merge in branch modelling using REST API. This information can help developers to use scripts to control their branches.

It should be documented.

Workaround:

There is a method for determining, and changing the Auto Merge State of a repository. This is an internal REST API that we don't have published. It hasn't been refined for public use, but it should work for what you're looking for.

Get Auto Merge Current State

curl -v -u <USER_NAME>:<PASSWORD> -X GET -H "Content-Type: application/json" "http://localhost:7990/bitbucket/rest/branch-utils/1.0/projects/{PROJECT_KEY}/repos/{REPO_SLUG}/automerge/enabled"

A return code of 404 indicates that Auto Merge is Disabled

Response: Auto Merge Not Enabled

> Content-Type: application/json
>
< HTTP/1.1 404 Not Found
< Server: Apache-Coyote/1.1

A return code of 200 indicated that Auto Merge is Enabled

Response: Auto Merge Enabled

< HTTP/1.1 200 
< X-AREQUESTID: @4KCVEWx1043x453x0

This is true even if the repository is enabled/ disabled at the project level.

Enable Auto Merge

curl -v -u <USER_NAME>:<PASSWORD> -X POST -H "Content-Type: application/json" "http://localhost:7990/bitbucket/rest/branch-utils/1.0/projects/{PROJECT_KEY}/repos/{REPO_SLUG}/automerge/enabled"

Disable Auto Merge

curl -v -u <USER_NAME>:<PASSWORD> -X DELETE -H "Content-Type: application/json" "http://localhost:7990/bitbucket/rest/branch-utils/1.0/projects/{PROJECT_KEY}/repos/{REPO_SLUG}/automerge/enabled"