update-dependencies pipeline failed for dotnet-monitor

[lbussell]

Pipeline run: build#2833119
Stack trace:

Failed to update dependencies:
System.AggregateException: One or more errors occurred. (Manifest does not contain a value for monitor|9.0|base-url|checksums|nightly)
 ---> System.ArgumentException: Manifest does not contain a value for monitor|9.0|base-url|checksums|nightly
   at Dotnet.Docker.ManifestHelper.GetVariableValue(String variableName, JObject variables) in /update-dependencies/eng/update-dependencies/ManifestHelper.cs:line 120
   at Dotnet.Docker.ManifestHelper.ResolveVariableValue(String variableName, JObject variables) in /update-dependencies/eng/update-dependencies/ManifestHelper.cs:line 112
   at Dotnet.Docker.ManifestHelper.<>c__DisplayClass2_0.<GetBaseUrls>b__0(String variable) in /update-dependencies/eng/update-dependencies/ManifestHelper.cs:line 34
   at System.Linq.Enumerable.IListSelectIterator`2.MoveNext()
   at System.Linq.Enumerable.IEnumerableWhereIterator`1.TryGetFirst(Boolean& found)
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
   at Dotnet.Docker.DockerfileShaUpdater.GetDotNetReleaseChecksumsShaAsync(String productDownloadUrl, String version) in /update-dependencies/eng/update-dependencies/DockerfileShaUpdater.cs:line 278
   at Dotnet.Docker.DockerfileShaUpdater.GetArtifactShaAsync(String downloadUrl) in /update-dependencies/eng/update-dependencies/DockerfileShaUpdater.cs:line 183
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Dotnet.Docker.DockerfileShaUpdater.TryGetDesiredValue(IEnumerable`1 dependencyBuildInfos, IEnumerable`1& usedBuildInfos) in /update-dependencies/eng/update-dependencies/DockerfileShaUpdater.cs:line 156
   at Microsoft.DotNet.VersionTools.Dependencies.FileRegexUpdater.GetUpdateTasks(IEnumerable`1 dependencyInfos)+MoveNext() in /_/src/Microsoft.DotNet.VersionTools/lib/src/Dependencies/FileRegexUpdater.cs:line 27
   at System.Linq.Enumerable.SelectManySingleSelectorIterator`2.MoveNext()
   at System.Linq.Enumerable.IteratorSelectIterator`2.MoveNext()
   at System.Linq.Enumerable.SelectManySingleSelectorIterator`2.MoveNext()
   at System.Collections.Generic.HashSet`1.UnionWith(IEnumerable`1 other)
   at System.Collections.Generic.HashSet`1..ctor(IEnumerable`1 collection, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.DistinctIterator`1.ToArray()
   at Microsoft.DotNet.VersionTools.Automation.DependencyUpdateUtils.Update(IEnumerable`1 updaters, IEnumerable`1 dependencyInfos) in /_/src/Microsoft.DotNet.VersionTools/lib/src/Automation/DependencyUpdateUtils.cs:line 24
   at Dotnet.Docker.SpecificCommand.UpdateFiles(IEnumerable`1 buildInfos, IEnumerable`1 updaters) in /update-dependencies/eng/update-dependencies/SpecificCommand.cs:line 171
   at Dotnet.Docker.SpecificCommand.ExecuteAsync(SpecificCommandOptions options) in /update-dependencies/eng/update-dependencies/SpecificCommand.cs:line 80
info: Microsoft.Hosting.Lifetime[0]
      Application is shutting down...

[lbussell]

[Triage] This is fixed with #6782.