The rpm-package-build task has been failing since late September. The cause appears to be an update to the mock package that removed the Fedora28 configuration we had been using. One possible approach is to update the .evergreen/build_snapshot_rpm.sh script to use Fedora 29 or 31. However, both of those failed for different reasons.
Fedora 31: https://evergreen.mongodb.com/task_log_raw/mongo_c_driver_releng_rpm_package_build_patch_062a0e1276203b6842cf390775fa661b8b191fff_5db0a4157742ae24da53efcc_19_10_23_19_03_50/0?type=T&text=true
Fedora 29: https://evergreen.mongodb.com/task_log_raw/mongo_c_driver_releng_rpm_package_build_patch_062a0e1276203b6842cf390775fa661b8b191fff_5db0a518d1fe0704e64496fe_19_10_23_19_08_08/0?type=T&text=true
Another possibility is to update the task to run on rhel80 now that it is available in Evergreen. However, this approach would require that the BUILD team update the rhel80 image to include the mock package.