Failing to build layer using `resources` leads to Index Out of Range

[tgolsson]

Describe the bug
Stacktrace:

Traceback (most recent call last):
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 623, in native_engine_generator_send
    res = rule.send(arg) if err is None else rule.throw(throw or err)
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/core/goals/repl.py", line 127, in run_repl
    request = await Get(ReplRequest, ReplImplementation, repl_impl)
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 118, in __await__
    result = yield self
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 623, in native_engine_generator_send
    res = rule.send(arg) if err is None else rule.throw(throw or err)
  File "<pants-cache-dir>/named_caches/pex_root/venvs/s/32db4f38/venv/lib/python3.9/site-packages/pants_backend_oci/goals/run.py", line 213, in run_oci_command_repl
    process = await Get(Process, RunImageBundleProcessRequest(request.targets[0], interactive=True))
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 118, in __await__
    result = yield self
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 623, in native_engine_generator_send
    res = rule.send(arg) if err is None else rule.throw(throw or err)
  File "<pants-cache-dir>/named_caches/pex_root/venvs/s/32db4f38/venv/lib/python3.9/site-packages/pants_backend_oci/goals/run.py", line 93, in prepare_run_image_bundle
    tool, image, rundir, shims = await MultiGet(
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 479, in MultiGet
    return await _MultiGet((__arg0, __arg1, __arg2, __arg3))
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 165, in __await__
    result = yield self.gets
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 623, in native_engine_generator_send
    res = rule.send(arg) if err is None else rule.throw(throw or err)
  File "<pants-cache-dir>/named_caches/pex_root/venvs/s/32db4f38/venv/lib/python3.9/site-packages/pants_backend_oci/language_target/python.py", line 119, in build_python_image
    base_image, umoci, *layers = await MultiGet(
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 464, in MultiGet
    return await _MultiGet((__arg0, __arg1, __arg2, __arg3, __arg4))
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 165, in __await__
    result = yield self.gets
  File "<cache-dir>/bindings/venvs/2.16.0/lib/python3.9/site-packages/pants/engine/internals/selectors.py", line 623, in native_engine_generator_send
    res = rule.send(arg) if err is None else rule.throw(throw or err)
  File "<pants-cache-dir>/named_caches/pex_root/venvs/s/32db4f38/venv/lib/python3.9/site-packages/pants_backend_oci/util_rules/layer.py", line 145, in build_image_layer
    raw_layer_digest, layer_name = real_layers[0]
IndexError: list index out of range

To Reproduce

Include a resources-target in a Python image.