Hi flagbit. Thanks for your reply.
We are using https://entagen.github.io/jenkins-build-per-branch/ to create new jobs per branch. This mean that the jobs will often be newly created. Maybe that is why the console out says

First time build. Skipping changelog.
Bitbucket notify on start failed: No change set to send to Bitbucket!

Could this be the problem? If so, is there a way to allow these new builds to also notify?

Hi yakobe,

so currently this plugin doesn't support your use case, since as you said most of your jobs will be newly created and there is no changes in your change set which commit can be set on Bitbucket. Anyways it something we would like to support in next days.

I'll personally notify you when this feature is supported.

Thanks for your feedback.

So do I understand well that your goal is to set the status on the checkedout commit?

Exactly that is what I want but my knowledge about the git-plugin, necessary to access to the las checkout commit, is limited and the solution is taking more than expected. I hope I can solve this problem next week and release a new version of the plugin with the solution to this problem and support for mercurial repositories.

As far as I know GitHub plugin already does that, so maybe it can give you some help.

Code changed in jenkins
User: Antonio Mansilla
Path:
src/main/java/org/jenkinsci/plugins/bitbucket/BitbucketBuildStatusNotifier.java
http://jenkins-ci.org/commit/bitbucket-build-status-notifier-plugin/9a8ca27818d7c2b074a63dfb40914deb8825711e
Log:
[Fix JENKINS-32519] Fix problem finding current revision

yakobe So finally I got the problem solved and changes got merged into master. It will be released next week or maybe sooner.

yakobe Last friday was released the version that fix this problem.

Please install the new version and try again if the problem is fixed.

The new build seems to work. We get messages like the following in our console log:

Sending build status INPROGRESS for commit 58c508d68d96ea6a237f90c4c599ade5849364c7 to BitBucket is done!

However, it still doesn't appear all the time in bitbucket. It seems this particularly noticable for pull requests. I remember you mentioned some issue with Forked repo's, but we are not working with forks. Any ideas?

yakobe That's fine. If the status doesn't appear in bitbucket is because it seems to not be supported by Bitbucket, I already created an issue at Bitbucket with following response:

I've checked with our Developers and build status simply isn't supported on PRs from repo forks right now. This is the reason you are not seeing the status on the PR. However, that should works fine if you are not working with forks.
Please let us know if there's anything else we can do for you.

All the best,
Renato Rudnicki
Atlassian Support

I'll resolve this issue since the problem was solved. If anyone face new problems with this, please create a new issue.