ExtensionDependencyChecker/Loader incorrectly recognizes different version of assemblies as same

[rynowak]

We see errors like the following in the Razor build server when upgrading packages

Extension assembly 'Microsoft.AspNetCore.Blazor.Razor.Extensions' at 'C:\Users\username\.nuget\packages\microsoft.aspnetcore.blazor.build\0.2.0-preview1-10195\tools\Microsoft.AspNetCore.Blazor.Razor.Extensions.dll' has a different ModuleVersionId than loaded assembly 'Microsoft.AspNetCore.Blazor.Razor.Extensions, Version=0.2.0.0, Culture=neutral, PublicKeyToken=null'
  Extensions could not be loaded. See output for details.
C:\Users\username\.nuget\packages\microsoft.aspnetcore.blazor.build\0.2.0-preview1-10195\targets\RazorCompilation.targets(179,5): error : rzc generate exited with code 1 

There are a few issues with this.

It would firstly be great to know which other assembly is loaded and where it was loaded from - my guess is that this happened when updating the packages used by our templates, or by mixing our templates with a repo-local build.

Secondly, I think this is just a bug. The assembly loading logic we use for Razor is supposed to be based on paths for 'top level' extensions, meaning that we should be able to load two copies of Microsoft.AspNetCore.Blazor.Razor.Extensions. We should investigate this and see if it's possible.

Lastly, this must not fail the build. We expect users to mix and match dependencies and this is intended to 'just work'.

[rynowak]

/cc @mkArtakMSFT @ajaybhargavb - it would be create if we could address all of these points for RC, I think the last point is a must fix.

[rynowak]

/cc @SteveSandersonMS FYI

[ajaybhargavb]

I'll investigate. @mkArtakMSFT, I'm self-assigning this.

[mkArtakMSFT]

Thanks @ajaybhargavb. Yes, please take it on.

[mkArtakMSFT]

@ajaybhargavb, please also cost this.

[ajaybhargavb]

@mkArtakMSFT, I merged aspnet/Razor#2277 which should fix what we wanted to fix for RC. We should leave this issue open though to address the underlying issue in a later release.

[mkArtakMSFT]

Thanks @ajaybhargavb! Moving!

[ajaybhargavb]

Lastly, this must not fail the build. We expect users to mix and match dependencies and this is intended to 'just work'.

This has been addressed in aspnet/Razor#2278. I'll change the title to reflect the work remaining.