Failure on Nuget Pack does not result in build failure

[AwaNoodle]

I have a nuspec file that is failing to pack correctly and visibly showing an error when the New-Packages task runs. The build completes with no errors listed in the results and looks like a completed build.

Task /Invoke-Commit/New-Packages
Will use version: 0.1.999 to build NuGet package
Attempting to build package from 'OneBuildTest.nuspec'. The replacement token 'id' has no value.
New-NuGetPackages : Whilst executing NuGet Pack on spec file C:\OneBuildTest\OneBuildTest.nuspec, NuGet.exe exited with error message: The replacement token 'id'
has no value.
At C:\OneBuildTest\OneBuild.build.ps1:65 char:19
+     New-NuGetPackages <<<<  -versionNumber $nuGetPackageVersion
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,New-NuGetPackages

1
Done /Invoke-Commit/New-Packages 00:00:00.8412285
Task /Invoke-Commit
Done /Invoke-Commit 00:00:14.5345897
WARNING: VersionNumber.xml file found, reading to set [major] and [minor] version numbers.
WARNING: Setting [major] version number to: 0.
WARNING: Setting [minor] version number to: 1.
Build succeeded with warnings. 7 tasks, 0 errors, 3 warnings 00:00:14.8433373

I've created this situation by using a .nuspec file next to the .sln file that is trying to use the $id$ definition which it won't find as it's not being packed with a csproj. Manually running nuget pack on the file results in the error as expected.

[lholman]

All merged in from PR #26