Automerge missing version of PullRequest in request to Bitbucket server

[philslab-ninja]

When the merge is being done this error happens:

Automerging failed: making request "POST http://xxx:7990/rest/api/1.0/projects/xxx/repos/xxx/pull-requests/2/merge" unexpected status code: 409, body: {"errors":[{"context":null,"message":"You are attempting to modify a pull request based on out-of-date information.","exceptionName":"com.atlassian.bitbucket.pull.PullRequestOutOfDateException","currentVersion":1,"expectedVersion":-1,"pullRequest":{"id":2,"version":1,"title":"Testing Atlantis Automerge" (...)

Seems this only affects bitbucket server (on-prem) and seems to be fixable by first polling for the current PR version, then using that version in the merge call.

see: https://confluence.atlassian.com/bitbucketserverkb/bitbucket-server-rest-api-for-merging-pull-request-fails-792309002.html

Thanks so much!

[philslab-ninja]

I have verified the fix on our infrastructure. Thanks!