Example fails if /bin not on PATH

[chrisburr]

On Arch Linux the example:

conda docker build -b frolvlad/alpine-glibc:latest -i example-image:123456 -o demo.tar numpy numba flask

fails with the error:

Executing transaction: done
Rolling back transaction: done

Exception('No compatible shell found!')
()

/.../sbin/chroot.fakechroot: line 147: 602419 Segmentation fault      (core dumped) env -u FAKECHROOT_BASE_ORIG FAKECHROOT_CMD_ORIG= LD_LIBRARY_PATH="$fakechroot_chroot_paths" FAKECHROOT_BASE="$fakechroot_chroot_base" "$fakechroot_chroot_chroot" "${@:1:$(($fakechroot_chroot_n - 1))}" "$fakechroot_chroot_final_newroot" "${@:$(($fakechroot_chroot_n + 1))}"
INFO:conda_docker.conda:building conda environment took 20.671 [s]
INFO:conda_docker.conda:adding conda environment in package layers
Traceback (most recent call last):
  File "/.../bin/conda-docker", line 11, in <module>
    load_entry_point('conda-docker', 'console_scripts', 'conda-docker')()
  File "/.../conda_docker/cli.py", line 121, in main
    cli(args)
  File "/.../conda_docker/cli.py", line 26, in cli
    args.func(args)
  File "/.../conda_docker/cli.py", line 114, in handle_conda_build
    layering_strategy=args.layering_strategy,
  File "/.../conda_docker/conda.py", line 635, in build_docker_environment
    layering_strategy=layering_strategy,
  File "/.../conda_docker/conda.py", line 582, in add_conda_layers
    image, hostpath, arcpath=arcpath, filter=filter, records=records
  File "/.../conda_docker/conda.py", line 548, in add_conda_package_layers
    with open(meta_path) as f:
FileNotFoundError: [Errno 2] No such file or directory: '/tmp/tmpi3vqxxt8/opt/conda/conda-meta/_libgcc_mutex-0.1-conda_forge.json'

This is because PATH is being propagated from the host and doesn't include /bin (in this alpine image the shell is /bin/bash). Appending /bin to PATH gets me slightly further (before hitting an unrelated segfault that I'm still debugging).

[chrisburr]

Ah the other segfault is "harmless":

conda-docker/conda_docker/conda.py

Lines 462 to 463 in 154a685

	# FIXME: this should reall be check_output(), but chroot or fakechroot is
	# giving some weird segfault after the install command completes ¯\_(ツ)_/¯

[scopatz]

@chrisburr - sorry for the late reply. Do you have a proposed fix?