netstandard.dll is missing for net46

[zivillian]

I am using this task to pseudolocalize our project with the task at https://github.com/ahdde/Psuedoizer/blob/dd872ad784f451db0dcf739aeee34eb444f44ed2/build/Pseudoizer.targets and the build fails within VS2017 15.7.6 with MSBuild 15.7.180.61344 when netstandard.dll is not in GAC. Building with dotnet build works without any error or warning.

Error   MSB4018 The "AddValidCultureNames" task failed unexpectedly.
System.IO.FileNotFoundException: Could not load file or assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. Das System kann die angegebene Datei nicht finden.
File name: 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'
   at InlineCode.AddValidCultureNames.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()

=== Pre-bind state information ===
LOG: DisplayName = netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51
 (Fully-specified)
LOG: Appbase = file:///C:/Program Files (x86)/Microsoft Visual Studio/2017/Enterprise/MSBuild/15.0/Bin/
LOG: Initial PrivatePath = NULL
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\15.0\Bin\MSBuild.exe.Config
LOG: Using host configuration file: 
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51
LOG: Attempting download of new URL file:///C:/Program Files (x86)/Microsoft Visual Studio/2017/Enterprise/MSBuild/15.0/Bin/netstandard.DLL.
LOG: Attempting download of new URL file:///C:/Program Files (x86)/Microsoft Visual Studio/2017/Enterprise/MSBuild/15.0/Bin/netstandard/netstandard.DLL.
LOG: Attempting download of new URL file:///C:/Program Files (x86)/Microsoft Visual Studio/2017/Enterprise/MSBuild/15.0/Bin/netstandard.EXE.
LOG: Attempting download of new URL file:///C:/Program Files (x86)/Microsoft Visual Studio/2017/Enterprise/MSBuild/15.0/Bin/netstandard/netstandard.EXE.

I was able to temporarily fix the error by copying the netstandard.dll from C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\lib\netstandard.dll to the net46 folder at C:\Users\<username>\.nuget\packages\roslyncodetaskfactory\2.0.7\build\net46