conda build: libarchive: cannot open shared object file: No such file or directory

I was getting the following error, attempting to run conda-build on a package, using a conda env:

Traceback (most recent call last):
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/bin/conda-build", line 7, in <module>
from conda_build.cli.main_build import main
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/conda_build/cli/main_build.py", line 18, in <module>
import conda_build.api as api
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/conda_build/api.py", line 22, in <module>
from conda_build.config import Config, get_or_merge_config, DEFAULT_PREFIX_LENGTH as _prefix_length
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/conda_build/config.py", line 17, in <module>
from .variants import get_default_variant
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/conda_build/variants.py", line 15, in <module>
from conda_build.utils import ensure_list, trim_empty_keys, get_logger
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/conda_build/utils.py", line 10, in <module>
import libarchive
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/libarchive/__init__.py", line 1, in <module>
from .entry import ArchiveEntry
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/libarchive/entry.py", line 6, in <module>
from . import ffi
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/site-packages/libarchive/ffi.py", line 27, in <module>
libarchive = ctypes.cdll.LoadLibrary(libarchive_path)
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/ctypes/__init__.py", line 426, in LoadLibrary
return self._dlltype(name)
File "/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/python3.6/ctypes/__init__.py", line 348, in __init__
self._handle = _dlopen(self._name, mode)
OSError: /nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/libarchive: cannot open shared object file: No such file or directory

The /lib directory does contain libarchive, both as a dynamic (.so) and static (.a) library. There turned out to be two relevant environment variables:

LIBARCHIVE=/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/libarchive
_CONDA_SET_LIBARCHIVE=LIBARCHIVE

A workaround is then to run

export LIBARCHIVE=/nfs/users/nfs_j/jl11/pathogen_nfs/large_installations/miniconda3/envs/conda_py36/lib/libarchive.so

There is probably a proper reason why this has happened and a permanent solution to the issue, but this works for now.