Jenkins parameterized build: build fails due to git parameter includes {^commit}

I would like to set up a parameterized build so the user can select branch and then press "build" to build that branch.

In configure I have added a git parameter "branch", like this:

I have then added the "branch" parameter as branch specifier in the pipeline definition like this:

When I start the build, I can select the branch without a problem. In this example /origin/feature/kvarntorp-test1.
But the build will fail with the following console output:

Started by user xxxx Lightweight checkout support not available,
falling back to full checkout. Checking out git
ssh://gitolite@tuleap.ermms.se/ermms/acm.git into
/var/lib/jenkins/workspace/6smCustomBuild@script to read
ci/jenkins/6msBuildAndTest.groovy

> git rev-parse –is-inside-work-tree # timeout=10 Fetching changes from the remote Git repository

> git config remote.origin.url ssh://gitolite@tuleap.ermms.se/ermms/acm.git # timeout=10 Fetching
upstream changes from ssh://gitolite@tuleap.ermms.se/ermms/acm.git

> git –version # timeout=10 using GIT_SSH to set credentials

> git fetch –tags –progress ssh://gitolite@tuleap.ermms.se/ermms/acm.git
+refs/heads/:refs/remotes/origin/

> git rev-parse /origin/feature/kvarntorp-test1^{commit} # timeout=10

> git rev-parse refs/remotes/origin//origin/feature/kvarntorp-test1^{commit} #
timeout=10

> git rev-parse /origin/feature/kvarntorp-test1^{commit} # timeout=10

ERROR: Couldn't find any revision to build. Verify the repository and
branch configuration for this job.

ERROR: Maximum checkout retry
attempts reached, aborting Finished: FAILURE

So Jenkins can not find the branch /origin/feature/kvarntorp-test1 because he is searching for /origin/feature/kvarntorp-test1^{commit}

Where did ^{commit} come from? Can I somehow remove the ^{commit} in the build configuration?
Have I configured the build wrong?

I have tried different names instead of "branch". Git PullRequest job failed. Couldn't find any revision to build. Verify the repository and branch configuration for this job suggests I should use sha1 with the default value "master". I tried sha1 as Git Parameter Name and ${sha1} as Branch Specifier. The build failed with the following console output:

hudson.plugins.git.GitException: Command "git fetch --tags --progress origin +refs/heads/${sha1}:refs/remotes/origin/${sha1} --prune" returned status code 128:
stdout: 
stderr: fatal: Couldn't find remote ref refs/heads/${sha1}
fatal: The remote end hung up unexpectedly

    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:2002)
    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1721)
    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.access$300(CliGitAPIImpl.java:72)
    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl$1.execute(CliGitAPIImpl.java:405)
    at jenkins.plugins.git.GitSCMFileSystem$BuilderImpl.build(GitSCMFileSystem.java:351)
    at jenkins.scm.api.SCMFileSystem.of(SCMFileSystem.java:196)
    at jenkins.scm.api.SCMFileSystem.of(SCMFileSystem.java:172)
    at org.jenkinsci.plugins.workflow.cps.CpsScmFlowDefinition.create(CpsScmFlowDefinition.java:108)
    at org.jenkinsci.plugins.workflow.cps.CpsScmFlowDefinition.create(CpsScmFlowDefinition.java:67)
    at org.jenkinsci.plugins.workflow.job.WorkflowRun.run(WorkflowRun.java:298)
    at hudson.model.ResourceController.execute(ResourceController.java:97)
    at hudson.model.Executor.run(Executor.java:429)
Finished: FAILURE