E           Engine traceback:
E             in select
E             in pants.backend.docker.docker_build_context.create_docker_build_context
E             in pants.backend.python.goals.package_pex_binary.package_pex_binary (src/python/proj/cli:bin)
E             in pants.backend.python.util_rules.pex.create_pex
E             in pants.backend.python.util_rules.pex.build_pex (src.python.proj.cli/bin.pex)
E             in pants.engine.process.fallible_to_exec_result_or_raise
E           Traceback (most recent call last):
E             File "/private/var/folders/8j/c8jf_msj009947wyw82xvdkw0000gn/T/process-executionVc609f/src/python/pants/engine/process.py", line 258, in fallible_to_exec_result_or_raise
E               raise ProcessExecutionFailure(
E           pants.engine.process.ProcessExecutionFailure: Process 'Building src.python.proj.cli/bin.pex' failed with exit code 127.
E           stdout:
E           
E           stderr:
E           env: python: No such file or directory