Describe the bug
When I run acr purge --filter <target> --ago 1d --untagged --dry-run --registry <myRegistry> it's saying it will delete manifests which are tagged?

To Reproduce
Steps to reproduce the behavior:

1. Have a container repository with at least 1x Tag and Multiple Manifests underneath.
2. In PowerShell, add these two variables: $registry = "YourRegHere" and $repo = "YourRepoHere"
3. Run az acr repository show-manifests --name $registry --repository $repo --output json | ConvertFrom-Json | Select-Object digest, tags
4. Review the output - In my case there is one tagged manifest and 30+ without tags.
5. Run acr purge --filter $repo --ago 1d --untagged -dry-run --registry $registry
6. Review the output - Note how the hash is in the dry run to be deleted!

Expected behavior
The name says --untagged so I expect it to only remove untagged manifests...

Screenshots
List of all manifests:

List of manifests being deleted (note how the tagged one is in there)

Any relevant environment information

• OS: Windows
• Version: 0.16, Revision: 2913fa4

Additional context
Also curious to know why these commands aren't part of the usual az suite? Seems a bit weird that it's a completely different executable.