Error out if `git log` fails in setup_ci_environment (#20231)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20231
ghimport-source-id: f58c44a52c719bf3c5cdcaa1f1e9624466423ace
Reviewed By: ezyang
Differential Revision: D15244497
Pulled By: zou3519
fbshipit-source-id: 87ca362aaa6a9040d32080b208272dacf7e45f63
