Nuspec file does not exist in package

I am using the following (rather basic) function.proj to reference a NuGet package:

```xml


netstandard2.0





```

However, it seems that the AFR is unable to restore this package, and fails with:

```
2019-11-27T12:14:06.024 [Information] Starting packages restore
2019-11-27T12:14:06.000 [Information] Restoring packages.
2019-11-27T12:14:06.030 [Information] Starting packages restore
2019-11-27T12:14:09.486 [Information] Restoring packages for D:\local\Temp\3e22b989-1d8e-45a0-91c4-ce23f1b194d4\function.proj...
2019-11-27T12:14:09.777 [Information] Restoring packages for D:\local\Temp\7cb06d64-89ce-45ea-8b01-058181167095\function.proj...
2019-11-27T12:14:11.367 [Information] D:\Program Files (x86)\dotnet\sdk\2.2.109\NuGet.targets(114,5): error NU5000: Nuspec file does not exist in package. [D:\local\Temp\3e22b989-1d8e-45a0-91c4-ce23f1b194d4\function.proj]
```

I've tried this a dozen times (since I'm doing it during a training), and all functions are in West Europe. Sometimes (meaning, some function apps deployed with exactly the same code) the issue is fixed by restarting the app (3 times out of 12). For the rest of 9 Function Apps, the restart doesn't fix the issue.

BTW, On the same note, I'd appreciate if the NuGet restore error would be logged as an error rather than an information message.

Start with the function.proj example and reproduce restoration of Azure.Storage.Blobs 12.0.0 using the reported .NET SDK 2.2.109 environment. Inspect the NU5000 failure at NuGet.targets line 114 and compare successful and failing Azure Functions deployments; done means package restore is reliable and the restore failure is logged as an error.

Written by the indexing model from the issue text.