kudu: Intermittent nuget restore failure.

I’ve got a project which deploys to 3 separate sites in West Europe, East US, and East Asia. For the last couple of weeks, the US instance fails the build on nuget restore with the following message:

Command: deploy.cmd
Handling .NET Web Application deployment.
All packages listed in packages.config are already installed.
All packages listed in packages.config are already installed.
Failed exitCode=-1073741818, command=nuget restore "D:\home\site\repository\Product\MySolution.sln"
An error has occurred during web site deployment.
Handling .NET Web Application deployment.\r\nAll packages listed in packages.config are already installed.\r\nAll packages listed in packages.config are already installed.\r\nFailed exitCode=-1073741818, command=nuget restore "D:\home\site\repository\Product\MySolution.sln"\r\nAn error has occurred during web site deployment.\r\nC:\Program Files (x86)\SiteExtensions\Kudu\48.41021.1874\bin\scripts\starter.cmd deploy.cmd

Running the nuget restore command manually in Kudu gives the “All packages listed in packages.config are already installed” message twice as above, but without the subsequent errors.

If I force a Retry/Sync via the management portal enough times and sometimes push the same commit again, it will eventually build successfully.

I have confirmed the following:

• All instances are on Kudu version 48.41021.1874.0
• There are no kudu version or msbuild overrides in place on any of the sites.
• Any SCM_* app settings are identical across all instances. I am using SCM_BUILD_ARGS, SCM_ALLOW_SUBMODULES, and SCM_SHALLOW_CLONE.

I’m mystified as to why, out of 3 seemingly identical instances, only the US one is giving me trouble. I’m not ruling out this being an Azure Websites problem but it seemed sensible to report it here first.