key error bug when invoking pex without arguments

[kaos]

$ ./pants -ldebug pex
15:55:18.96 [DEBUG] acquiring lock: <pants.pantsd.lock.OwnerPrintingInterProcessFileLock object at 0x10a7f1f70>
15:55:18.96 [DEBUG] releasing lock: <pants.pantsd.lock.OwnerPrintingInterProcessFileLock object at 0x10a7f1f70>
15:55:18.96 [DEBUG] Connecting to pantsd on port 62729
15:55:18.97 [DEBUG] Connecting to pantsd on port 62729 attempt 1/3
15:55:18.97 [DEBUG] Connected to pantsd
15:55:19.00 [DEBUG] Launching 1 roots (poll=false).
15:55:19.02 [DEBUG] Starting: pants.backend.python.util_rules.pex.build_pex
15:55:19.02 [DEBUG] Starting: Find Python interpreter to bootstrap PEX
15:55:19.02 [DEBUG] Canceled: pants.backend.python.util_rules.pex.build_pex
15:55:19.02 [DEBUG] Starting: Find Python interpreter for constraints
15:55:19.02 [DEBUG] Canceled: Find Python interpreter for constraints
15:55:19.02 [DEBUG] Starting: Find Python interpreter to bootstrap PEX
15:55:19.02 [DEBUG] Completed: Find Python interpreter to bootstrap PEX - Selected /Users/aadt/.cache/pants/pants_dev_deps/Darwin.x86_64.i386.py38.venv/bin/python to bootstrap PEXes with.
15:55:19.02 [DEBUG] Completed: Find Python interpreter to bootstrap PEX - Selected /Users/aadt/.cache/pants/pants_dev_deps/Darwin.x86_64.i386.py38.venv/bin/python to bootstrap PEXes with.
15:55:19.02 [DEBUG] Starting: pants.backend.python.util_rules.pex.build_pex
15:55:19.02 [DEBUG] Starting: Find Python interpreter for constraints
15:55:19.02 [DEBUG] Completed: Find Python interpreter for constraints - Selected /usr/local/Cellar/[email protected]/3.8.5/Frameworks/Python.framework/Versions/3.8/bin/python3.8 to run PEXes with.
15:55:19.02 [DEBUG] Completed: pants.backend.python.util_rules.pex.build_pex
15:55:19.02 [DEBUG] computed 1 nodes in 0.028035 seconds. there are 127 total nodes.
15:55:19.07 [DEBUG] Launching 1 roots (poll=false).
15:55:19.07 [DEBUG] computed 1 nodes in 0.000628 seconds. there are 127 total nodes.
15:55:19.13 [DEBUG] specs are: Specs(address_specs=AddressSpecs(literals=(), globs=(), filter_by_global_options=True), filesystem_specs=FilesystemSpecs(includes=(), ignores=()))
15:55:19.13 [DEBUG] changed_options are: ChangedOptions(since=None, diffspec=None, dependees=<DependeesOption.NONE: 'none'>)
15:55:19.13 [DEBUG] Launching 1 roots (poll=false).
15:55:19.13 [DEBUG] computed 1 nodes in 0.004937 seconds. there are 788 total nodes.
15:55:19.13 [DEBUG] BuildSense plugin is disabled.
15:55:19.13 [ERROR] Exception caught: (builtins.KeyError)
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/bin/local_pants_runner.py", line 234, in _run_inner
    return self._perform_run(goals)
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/bin/local_pants_runner.py", line 173, in _perform_run
    return self._perform_run_body(goals, poll=False)
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/bin/local_pants_runner.py", line 190, in _perform_run_body
    return self.graph_session.run_goal_rules(
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/init/engine_initializer.py", line 122, in run_goal_rules
    goal_product = self.goal_map[goal]

Exception message: 'pex'
Traceback (most recent call last):
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/bin/local_pants_runner.py", line 234, in _run_inner
    return self._perform_run(goals)
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/bin/local_pants_runner.py", line 173, in _perform_run
    return self._perform_run_body(goals, poll=False)
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/bin/local_pants_runner.py", line 190, in _perform_run_body
    return self.graph_session.run_goal_rules(
  File "/Users/aadt/src/github/kaos/pants/src/python/pants/init/engine_initializer.py", line 122, in run_goal_rules
    goal_product = self.goal_map[goal]
KeyError: 'pex'

(Use --no-process-execution-local-cleanup to inspect chroots. See https://www.pantsbuild.org/v2.7/docs/troubleshooting for common issues. Consider reaching out for help: https://www.pantsbuild.org/v2.7/docs/getting-help.)