When we backported 'featureFlagBucketUnpackWithSort' to the 5.0 branch, it had already been released on 6.0. To avoid changing the 'version' field of the feature flag retroactively, we gave the 5.0 feature flag a different name: 'featureFlagBucketUnpackWithSort50'.

Multiversion tests on the v6.0 branch run against both 5.0 and 6.0 binaries. When these tests check for the feature flag, they should check both names.