i am trying to package azure cli as pex so when i do:

pip install azure-cli
python -m azure.cli

everything works as expected. but when i try this

pex azure-cli -m azure.cli -o az
./az

i get this error

Traceback (most recent call last):
  File "/az/.bootstrap/pex/pex.py", line 396, in execute
  File "/az/.bootstrap/pex/pex.py", line 328, in _wrap_coverage
  File "/az/.bootstrap/pex/pex.py", line 359, in _wrap_profiling
  File "/az/.bootstrap/pex/pex.py", line 447, in _execute
  File "/az/.bootstrap/pex/pex.py", line 544, in execute_entry
  File "/az/.bootstrap/pex/pex.py", line 551, in execute_module
  File "/usr/local/lib/python3.7/runpy.py", line 201, in run_module
    mod_name, mod_spec, code = _get_module_details(mod_name)
  File "/usr/local/lib/python3.7/runpy.py", line 109, in _get_module_details
    __import__(pkg_name)
  File "/root/.pex/installed_wheels/70125b7d832d1ca0e01f7578de3d97524756eb0e/azure_cli_core-2.4.0-py3-none-any.whl/azure/__init__.py", line 5, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

how do i debug and fix this?