Fix data build script
The subprocess call (which should have been using run
) uses the -u
bash option, which stops the script at the first sight of an unset
variable... but also doesn't set the variable expected by the very
docstring example.
We also reset the environment so that the hg script is not influenced by user configuration, which was a second source of breakage.
Migrated from D5815 (view on Phabricator)