Non-deterministic test failure

[ryan-williams]

failued run, passed on re-run

=================================== FAILURES ===================================
______________________ test_tmp_clone_remote_push_changes ______________________

    def test_tmp_clone_remote_push_changes():
        # set this HAILSTONE_SSH_URL to a different fork or repo if developing without access to this one
        url = env.get('HAILSTONE_SSH_URL', 'git@gitlab.com:gsmo/examples/hailstone.git')
        branch = 'tmp'
        sha0 = 'e0add3d'
        with git.clone.tmp(url, branch=branch, ref=sha0, push=True) as cwd:
            tmpdir = cwd
            check(cwd=cwd, name='hailstone', shas={sha0: (None, branch)})
>           sha1 = commit_file('test1.txt', ['111', '222'], sha0, fmt='%H')

utz/tests/test_git.py:91: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/opt/hostedtoolcache/Python/3.9.17/x64/lib/python3.9/contextlib.py:126: in __exit__
    next(self.gen)
utz/git/clone.py:124: in tmp
    run(*cmd)
utz/process/__init__.py:[86](https://github.com/runsascoded/utz/actions/runs/5744848858/job/15571857304#step:6:87): in run
    check_call(cmd, **kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

popenargs = (['git', 'push', 'origin', 'tmp:tmp'],), kwargs = {}, retcode = 1
cmd = ['git', 'push', 'origin', 'tmp:tmp']

    def check_call(*popenargs, **kwargs):
        """Run command with arguments.  Wait for command to complete.  If
        the exit code was zero then return, otherwise raise
        CalledProcessError.  The CalledProcessError object will have the
        return code in the returncode attribute.
    
        The arguments are the same as for the call function.  Example:
    
        check_call(["ls", "-l"])
        """
        retcode = call(*popenargs, **kwargs)
        if retcode:
            cmd = kwargs.get("args")
            if cmd is None:
                cmd = popenargs[0]
>           raise CalledProcessError(retcode, cmd)
E           subprocess.CalledProcessError: Command '['git', 'push', 'origin', 'tmp:tmp']' returned non-zero exit status 1.

/opt/hostedtoolcache/Python/3.9.17/x64/lib/python3.9/subprocess.py:373: CalledProcessError
----------------------------- Captured stdout call -----------------------------
[tmp 6c[87](https://github.com/runsascoded/utz/actions/runs/5744848858/job/15571857304#step:6:88)79e] add test1.txt: ['111', '222']
 1 file changed, 2 insertions(+)
 create mode [100](https://github.com/runsascoded/utz/actions/runs/5744848858/job/15571857304#step:6:101)644 test1.txt
----------------------------- Captured stderr call -----------------------------
Running: git clone --recurse-submodules git@gitlab.com:gsmo/examples/hailstone.git /tmp/tmpx35oqbjb/hailstone
Cloning into '/tmp/tmpx35oqbjb/hailstone'...
Running: git show-ref --verify --quiet refs/heads/tmp
Running: git checkout -b tmp e0add3d
Switched to a new branch 'tmp'
Running: git status --short
Running: git log -n1 --format=%h
Running: git log -n1 --format=%h tmp
Running: git add test1.txt
Running: git commit -m 'add test1.txt: ['"'"'[111](https://github.com/runsascoded/utz/actions/runs/5744848858/job/15571857304#step:6:112)'"'"', '"'"'222'"'"']'
Running: git log -n1 --format=%h 'HEAD^'
Running: git log -n1 --format=%H
Running: git push origin tmp:tmp
remote: error: cannot lock ref 'refs/heads/tmp': reference already exists        
To gitlab.com:gsmo/examples/hailstone.git
 ! [remote rejected] tmp -> tmp (failed to update ref)
error: failed to push some refs to 'gitlab.com:gsmo/examples/hailstone.git'
=============================== warnings summary ===============================
utz/tests/test_ctx.py:8
  /home/runner/work/utz/utz/utz/tests/test_ctx.py:8: PytestCollectionWarning: cannot collect test class 'TestCtx' because it has a __init__ constructor (from: utz/tests/test_ctx.py)
    class TestCtx(AbstractContextManager):

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
FAILED utz/tests/test_git.py::test_tmp_clone_remote_push_changes - subprocess.CalledProcessError: Command '['git', 'push', 'origin', 'tmp:tmp']' returned non-zero exit status 1.
=================== 1 failed, 47 passed, 1 warning in 59.12s ===================