hackage-doc-tarball job failing on nightly
See: https://gitlab.haskell.org/ghc/ghc/-/jobs/1547778
Traceback (most recent call last):
File "./upload_ghc_libs.py", line 245, in <module>
main()
File "./upload_ghc_libs.py", line 226, in main
pkg_meta = prepare_pkg(args.bindist, pkg)
File "./upload_ghc_libs.py", line 187, in prepare_pkg
p1 = prepare_sdist(pkg)
File "./upload_ghc_libs.py", line 128, in prepare_sdist
run(['cabal', 'sdist'], cwd=pkg.path, check=True)
File "/usr/lib/python3.7/subprocess.py", line 487, in run
output=stdout, stderr=stderr)