Docfx failing under AppVeyor

[jskeet]

Now that AppVeyor has updated to .NET Core 2.0, docfx can't find the msbuild properties files.

00:32:10 Building docs for Google.Cloud.BigQuery.V2
[17-08-18 07:32:16.523]Warning:[ExtractMetadata]Workspace failed with: [Failure] Msbuild failed when processing the file 'C:\projects\google-cloud-dotnet\apis\Google.Cloud.BigQuery.V2\Google.Cloud.BigQuery.V2\Google.Cloud.BigQuery.V2.csproj' with message: The imported project "C:\projects\google-cloud-dotnet\packages\docfx.2.22.3\Sdks\Microsoft.NET.Sdk\Sdk\Sdk.props" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk.  C:\projects\google-cloud-dotnet\apis\Google.Cloud.BigQuery.V2\Google.Cloud.BigQuery.V2\Google.Cloud.BigQuery.V2.csproj

This is our instance of this docfx issue which in turn comes from this msbuild issue. The suggested solution is to install VS2017 instead of just the build tools. Not easy on CI...

The good news is that I suspect the Sdk.props file is on disk somewhere, but we need to find it and set an appropriate environment variable.

[jskeet]

Setting MSBuildSDKsPath = "C:\Program Files\dotnet\sdk\1.0.4\Sdks" moves the problem on a bit:

[17-08-18 08:21:45.893]Warning:[ExtractMetadata]Workspace failed with: [Failure] Msbuild failed when processing the file 'C:\projects\google-cloud-dotnet\apis\Google.Cloud.BigQuery.V2\Google.Cloud.BigQuery.V2\Google.Cloud.BigQuery.V2.csproj' with message: The imported project "C:\Program Files (x86)\MSBuild\2.0\Microsoft.Common.props" was not found. Confirm that the path in the declaration is correct, and that the file exists on disk. C:\Program Files\dotnet\sdk\1.0.4\Sdks\Microsoft.NET.Sdk\Sdk\Sdk.props

The fact that it's looking for MSBuild 2.0 is weird.
Trying to set more environment variables...

[jskeet]

Closing as we'll run it on Jenkins instead.