Branch name can exceed key parameter length limit on Bitbucket Cloud

[piroux]

It seems that the Bitbucket Cloud API has some length limit on the key path parameter of the query used to create a new reference for a build.

Currently the entire branch name is used as the key, so that it triggers the error in the get step only for branch names exceeding 40 characters.

selected worker: e6b7913ef80d
--DEBUG MODE--
Commit: b59379ac055dd34c8d3e95918169da4d4e83955b
Build URL: http://***/builds/2
Set build status: {'state': 'INPROGRESS', 'key': 'branch-feature-< ... very long branch name>', 'name': 'branch-feature-< ... very long branch name> #2', 'url': 'http://***/builds/2', 'description': 'Concourse CI build, hijack as #74'}
Request result: {'type': 'error', 'error': {'fields': {'key': ['Ensure this value has at most 40 characters (it has 58).']}, 'message': 'key: Ensure this value has at most 40 characters (it has 58).'}}
HTTP 400 Bad Request - something's gone wrong. Set `source.debug: true` to show details

I do not know if Bitbucket Server is affected in the same way.