Network issues hit during build restore step are silently ignored

[jkotas]

Actual behavior: Network issues hit during build restore step are silently ignored that leads to arbitrary errors later. Examples:

• build -s libs.pretest fails on Linux #44710
• build fails with "Invalid restore input. Duplicate frameworks found: 'net6.0-windows7.0, net6.0, net6.0'" #44708

Expected behavior: Network issues hit during build restore step are clearly reported.

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Issue Details

Description:	Actual behavior: Network issues hit during build restore step are silently ignored that leads to arbitrary errors later. Examples: build -s libs.pretest fails on Linux #44710 build fails with "Invalid restore input. Duplicate frameworks found: 'net6.0-windows7.0, net6.0, net6.0'" #44708 Expected behavior: Network issues hit during build restore step are clearly reported.
Author:	jkotas
Assignees:	-
Labels:	area-Infrastructure, untriaged
Milestone:	-

[ViktorHofer]

Possibly related or even the cause: dotnet/arcade#5172

[ViktorHofer]

@jkotas did you see any warnings or were those swallowed?

[jkotas]

I do not remember seeing any warnings.

[ViktorHofer]

cc @nkolev92 from the NuGet team. Are you aware of restore failures (in this case 429s when requesting the index.json) not being propagated and the build silently continuing which results in missing imports because the nuget generated props and targets files missing?

[nkolev92]

Haven't see anything like that.
Any repro/logs to help us investigate would be great.

[ViktorHofer]

In dotnet/runtime we are now down to two up-front restore invocations instead of previously three (tasks were restored extra) which will likely help with this issue. I haven't observed such behavior in any recent build but it definitely happened so let's keep the issue open to refcount the hits.