Investigate Template Baseline tests errors

[HaoK]

The template baseline tests logs all seem to have an exception:

This is indicative of something being broken

[0.001s] [Templates.Test.BaselineTest] [Information] Acquired DotNetNewLock
[0.001s] [Templates.Test.BaselineTest] [Information] ==> dotnet new razor -au None --debug:custom-hive "Hives\.templateEngine" -o C:\h\w\A73308F6\w\9DA308AE\e\Templates\BaseFolder\AspNet.xhudlncbxfg [C:\h\w\A73308F6\w\9DA308AE\e\]
[0.392s] [Templates.Test.BaselineTest] [Information] [ERROR] Warning: Failed to scan "[Hives\.templateEngine\packages\Microsoft.DotNet.Web.ItemTemplates.6.0.0-ci.nupkg, 4/21/2021 5:58:53 AM]":
[0.400s] [Templates.Test.BaselineTest] [Information] [ERROR] System.Exception: source location Hives\.templateEngine\packages\Microsoft.DotNet.Web.ItemTemplates.6.0.0-ci.nupkg is not supported, or doesn't exist.
[0.400s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.Scanner.GetOrCreateMountPointScanInfoForInstallSource(String sourceLocation) in Microsoft.TemplateEngine.Edge.dll:token 0x6000100+0xb8
[0.406s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.Scanner.Scan(String sourceLocation) in Microsoft.TemplateEngine.Edge.dll:token 0x60000ff+0x13
[0.408s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.SettingsLoader.RebuildCacheFromSettingsIfNotCurrent(Boolean forceRebuild) in Microsoft.TemplateEngine.Edge.dll:token 0x600010e+0x0
[0.408s] [Templates.Test.BaselineTest] [Information] [ERROR] Warning: Failed to scan "[Hives\.templateEngine\packages\Microsoft.DotNet.Web.ProjectTemplates.6.0.6.0.0-ci.nupkg, 4/21/2021 5:58:53 AM]":
[0.408s] [Templates.Test.BaselineTest] [Information] [ERROR] System.Exception: source location Hives\.templateEngine\packages\Microsoft.DotNet.Web.ProjectTemplates.6.0.6.0.0-ci.nupkg is not supported, or doesn't exist.
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.Scanner.GetOrCreateMountPointScanInfoForInstallSource(String sourceLocation) in Microsoft.TemplateEngine.Edge.dll:token 0x6000100+0xb8
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.Scanner.Scan(String sourceLocation) in Microsoft.TemplateEngine.Edge.dll:token 0x60000ff+0x13
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.SettingsLoader.RebuildCacheFromSettingsIfNotCurrent(Boolean forceRebuild) in Microsoft.TemplateEngine.Edge.dll:token 0x600010e+0x0
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR] Warning: Failed to scan "[Hives\.templateEngine\packages\Microsoft.DotNet.Web.Spa.ProjectTemplates.6.0.6.0.0-ci.nupkg, 4/21/2021 5:58:53 AM]":
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR] System.Exception: source location Hives\.templateEngine\packages\Microsoft.DotNet.Web.Spa.ProjectTemplates.6.0.6.0.0-ci.nupkg is not supported, or doesn't exist.
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.Scanner.GetOrCreateMountPointScanInfoForInstallSource(String sourceLocation) in Microsoft.TemplateEngine.Edge.dll:token 0x6000100+0xb8
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.Scanner.Scan(String sourceLocation) in Microsoft.TemplateEngine.Edge.dll:token 0x60000ff+0x13
[0.409s] [Templates.Test.BaselineTest] [Information] [ERROR]    at Microsoft.TemplateEngine.Edge.Settings.SettingsLoader.RebuildCacheFromSettingsIfNotCurrent(Boolean forceRebuild) in Microsoft.TemplateEngine.Edge.dll:token 0x600010e+0x0
[1.081s] [Templates.Test.BaselineTest] [Information] The template "ASP.NET Core Web App" was created successfully.
[1.081s] [Templates.Test.BaselineTest] [Information] This template contains technologies from parties other than Microsoft, see https://aka.ms/aspnetcore/6.0-third-party-notices for details.
[1.081s] [Templates.Test.BaselineTest] [Information] 
[1.081s] [Templates.Test.BaselineTest] [Information] Processing post-creation actions...
[1.082s] [Templates.Test.BaselineTest] [Information] Running 'dotnet restore' on C:\h\w\A73308F6\w\9DA308AE\e\Templates\BaseFolder\AspNet.xhudlncbxfg\AspNet.xhudlncbxfg.csproj...
[1.515s] [Templates.Test.BaselineTest] [Information]   Determining projects to restore...
[1.738s] [Templates.Test.BaselineTest] [Information]   Restored C:\h\w\A73308F6\w\9DA308AE\e\Templates\BaseFolder\AspNet.xhudlncbxfg\AspNet.xhudlncbxfg.csproj (in 92 ms).
[1.749s] [Templates.Test.BaselineTest] [Information] Restore succeeded.
[1.749s] [Templates.Test.BaselineTest] [Information] 
[1.770s] [Templates.Test.BaselineTest] [Information] Process exited.
[1.770s] [Templates.Test.BaselineTest] [Information] Released DotNetNewLock
[1.772s] [TestLifetime] [Information] Finished test Template_Produces_The_Right_Set_Of_FilesAsync-new_razor_-au_None-System.String[] in 1.7709911s

[HaoK]

@phenning this is the issue and error message we are seeing with our custom template hive

[HaoK]

The code where we are installing to the template engine is here: https://github.com/dotnet/aspnetcore/blob/main/src/ProjectTemplates/Shared/TemplatePackageInstaller.cs#L88