Cannot trigger build on a branch with slash in name using API

Feedback & Bug Reports
1

GET https://circleci.com/api/v1.1/project/bitbucket/…/tree/release%2F3.5 works just fine.
POST https://circleci.com/api/v1.1/project/bitbucket/…/tree/release%2F3.5 gives me
{
“message”: “Branch not found”
}

2

Likewise having the same issue. Anyone got a work around for this?