Building a package on Linux fails if nuspec does not have files element

[TheCakeIsNaOH]

What You Are Seeing?

When running on Mono on Linux, if the .nuspec does not have a <files> element, building a package with choco pack can fail with the error:
This partUri is already contained in the package

What is Expected?

That choco pack should work even if there is not a <files> element.

How Did You Get This To Happen? (Steps to Reproduce)

Run choco pack to build a package where the .nuspec does not have a <files> element.

Output Log

Full Log Output

/no-files-zfsin$ choco pack --verbose --debug
Chocolatey v0.11.2-22-g19d7dd10
Chocolatey is running on Linux v 5.10.0.0
Attempting to delete file "/opt/chocolatey/chocolatey.dll.old".
Attempting to delete file "/opt/chocolatey/choco.exe.old".
Command line: /opt/chocolatey/choco.exe pack --verbose --debug --allow-unofficial
Received arguments: pack --verbose --debug --allow-unofficial
RemovePendingPackagesTask is now ready and waiting for PreRunMessage.
Sending message 'PreRunMessage' out if there are subscribers...
[Pending] Removing all pending packages that should not be considered installed...
Performing validation checks.
Global Configuration Validation Checks:
 - Package Exit Code / Exit On Reboot = Checked
System State Validation Checks:
The source 'https://chocolatey.org/api/v2/' evaluated to a 'normal' source type

NOTE: Hiding sensitive configuration data! Please double and triple
 check to be sure no sensitive data is shown, especially if copying
 output to a gist for review.
Configuration: CommandName='pack'|CacheLocation='/tmp/chocolatey'|
ContainsLegacyPackageInstalls='True'|
CommandExecutionTimeoutSeconds='2700'|WebRequestTimeoutSeconds='30'|
Sources='https://chocolatey.org/api/v2/'|SourceType='normal'|
Debug='True'|Verbose='True'|Trace='False'|Force='False'|Noop='False'|
HelpRequested='False'|UnsuccessfulParsing='False'|RegularOutput='True'|
QuietOutput='False'|PromptForConfirmation='False'|
AcceptLicense='False'|
AllowUnofficialBuild='True'|AllVersions='False'|
SkipPackageInstallProvider='False'|Prerelease='False'|ForceX86='False'|
OverrideArguments='False'|NotSilent='False'|
ApplyPackageParametersToDependencies='False'|
ApplyInstallArgumentsToDependencies='False'|IgnoreDependencies='False'|
AllowMultipleVersions='False'|AllowDowngrade='False'|
ForceDependencies='False'|Information.PlatformType='Linux'|
Information.PlatformVersion='5.10.0.0'|
Information.PlatformName='Linux'|
Information.ChocolateyVersion='0.12.0.0'|
Information.ChocolateyProductVersion='0.11.2-22-g19d7dd10'|
Information.FullName='chocolatey, Version=0.12.0.0, Culture=neutral, PublicKeyToken=fd112f53c3ab578c'|

Information.Is64BitOperatingSystem='True'|
Information.Is64BitProcess='True'|Information.IsInteractive='False'|
Information.UserName='REDACTED'|Information.UserDomainName='REDACTED'|
Information.IsUserAdministrator='False'|
Information.IsUserSystemAccount='False'|
Information.IsUserRemoteDesktop='False'|
Information.IsUserRemote='True'|
Information.IsProcessElevated='False'|
Information.IsLicensedVersion='False'|Information.LicenseType='Foss'|
Information.CurrentDirectory='/path/no-files-zfsin'|

Features.AutoUninstaller='True'|Features.ChecksumFiles='True'|
Features.AllowEmptyChecksums='False'|
Features.AllowEmptyChecksumsSecure='True'|
Features.FailOnAutoUninstaller='False'|
Features.FailOnStandardError='False'|Features.UsePowerShellHost='True'|
Features.LogEnvironmentValues='False'|Features.LogWithoutColor='False'|
Features.VirusCheck='False'|
Features.FailOnInvalidOrMissingLicense='False'|
Features.IgnoreInvalidOptionsSwitches='True'|
Features.UsePackageExitCodes='True'|
Features.UseEnhancedExitCodes='False'|
Features.UseFipsCompliantChecksums='False'|
Features.ShowNonElevatedWarnings='True'|
Features.ShowDownloadProgress='True'|
Features.StopOnFirstPackageFailure='False'|
Features.UseRememberedArgumentsForUpgrades='False'|
Features.IgnoreUnfoundPackagesOnUpgradeOutdated='False'|
Features.SkipPackageUpgradesWhenNotInstalled='False'|
Features.RemovePackageInformationOnUninstall='False'|
Features.ExitOnRebootDetected='False'|
Features.LogValidationResultsOnWarnings='True'|
Features.UsePackageRepositoryOptimizations='True'|
Features.ScriptsCheckLastExitCode='False'|
ListCommand.LocalOnly='False'|
ListCommand.IdOnly='False'|ListCommand.IncludeRegistryPrograms='False'|
ListCommand.PageSize='25'|ListCommand.Exact='False'|
ListCommand.ByIdOnly='False'|ListCommand.ByTagOnly='False'|
ListCommand.IdStartsWith='False'|ListCommand.OrderByPopularity='False'|
ListCommand.ApprovedOnly='False'|
ListCommand.DownloadCacheAvailable='False'|
ListCommand.NotBroken='False'|
ListCommand.IncludeVersionOverrides='False'|
UpgradeCommand.FailOnUnfound='False'|
UpgradeCommand.FailOnNotInstalled='False'|
UpgradeCommand.NotifyOnlyAvailableUpgrades='False'|
UpgradeCommand.ExcludePrerelease='False'|
NewCommand.AutomaticPackage='False'|
NewCommand.UseOriginalTemplate='False'|SourceCommand.Command='unknown'|
SourceCommand.Priority='0'|SourceCommand.BypassProxy='False'|
SourceCommand.AllowSelfService='False'|
SourceCommand.VisibleToAdminsOnly='False'|
FeatureCommand.Command='unknown'|ConfigCommand.Command='unknown'|
ApiKeyCommand.Remove='False'|PinCommand.Command='unknown'|
OutdatedCommand.IgnorePinned='False'|
ExportCommand.IncludeVersionNumbers='False'|Proxy.BypassOnLocal='True'|

Chocolatey is not an official build (bypassed with --allow-unofficial).
 If you are seeing this message and it is not expected, your system may
 now be in a bad state. Only official builds are to be trusted.

_ Chocolatey:ChocolateyPackCommand - Normal Run Mode _
Attempting to build package from 'zfsin.nuspec'.
zfsin.nuspec
Attempting to delete file "/path/no-files-zfsin/zfsin.0.24-eljun.nupkg".
Sending message 'PostRunMessage' out if there are subscribers...
Not able to cleanup NuGet temp folders. Failure was Path to combine cannot be empty. Tried to combine null with ''. Method called from 'delete_directory'
Chocolatey had an error occur:
System.InvalidOperationException: This partUri is already contained in the package
  at System.IO.Packaging.Package.CreatePart (System.Uri partUri, System.String contentType, System.IO.Packaging.CompressionOption compressionOption) [0x0001b] in <8f8261ee75c34c9cb0a71d0993973faa>:0
  at NuGet.PackageBuilder.CreatePart (System.IO.Packaging.Package package, System.String path, System.IO.Stream sourceStream) [0x0001e] in <0446c6bfcd824d528312261f49bc47fe>:0
  at NuGet.PackageBuilder.WriteFiles (System.IO.Packaging.Package package) [0x00043] in <0446c6bfcd824d528312261f49bc47fe>:0
  at NuGet.PackageBuilder.Save (System.IO.Stream stream) [0x000ca] in <0446c6bfcd824d528312261f49bc47fe>:0
  at chocolatey.infrastructure.app.nuget.NugetPack.BuildPackage (NuGet.PackageBuilder builder, chocolatey.infrastructure.filesystem.IFileSystem fileSystem, System.String outputPath) [0x00056] in <845de20ca2654563911ec50dad3fc2b7>:0
  at chocolatey.infrastructure.app.services.NugetService.pack_run (chocolatey.infrastructure.app.configuration.ChocolateyConfiguration config) [0x001fb] in <845de20ca2654563911ec50dad3fc2b7>:0
  at chocolatey.infrastructure.app.services.ChocolateyPackageService.pack_run (chocolatey.infrastructure.app.configuration.ChocolateyConfiguration config) [0x00020] in <845de20ca2654563911ec50dad3fc2b7>:0
  at chocolatey.infrastructure.app.commands.ChocolateyPackCommand.run (chocolatey.infrastructure.app.configuration.ChocolateyConfiguration configuration) [0x00000] in <845de20ca2654563911ec50dad3fc2b7>:0
  at chocolatey.infrastructure.app.runners.GenericRunner.run (chocolatey.infrastructure.app.configuration.ChocolateyConfiguration config, SimpleInjector.Container container, System.Boolean isConsole, System.Action`1[T] parseArgs) [0x000e4] in <845de20ca2654563911ec50dad3fc2b7>:0
  at chocolatey.infrastructure.app.runners.ConsoleApplication.run (System.String[] args, chocolatey.infrastructure.app.configuration.ChocolateyConfiguration config, SimpleInjector.Container container) [0x000d6] in <845de20ca2654563911ec50dad3fc2b7>:0
  at chocolatey.console.Program.Main (System.String[] args) [0x0036a] in <a6fa8517b92d4fc18e56c6cf1219f2c9>:0
Exiting with 1