Source download from Visual Studio fails on server accepting TLS>1.0 connections only

Steps to reproduce

Index a pdb with Powershell and a https url
Configure the web server to reject SSL3 and TLS1.0 connections
Attempt to access the source file when debugging in Visual Studio

Platform: Windows 10, Visual Studio 2017

Expected behaviour

The source file should be downloaded and opened by Visual Studio.

Actual behaviour

The file fails to download. When enabling "Print source server diagnostic messages...", the following log is visible (urls removed):

powershell invoke-command -scriptblock {$webClient = New-Object System.Net.WebClient; $webClient.UseDefaultCredentials = $true; $webClient.DownloadFile('[...], '[...]');}
Exception calling "DownloadFile" with "2" argument(s): "The underlying connection was closed: An unexpected error
occurred on a send."
At line:1 char:182
+ ... ls = $true; $webClient.DownloadFile('[...] ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : WebException

Comments

This is caused by Visual Studio opening a powershell instance with some strange context when downloading files from source server (probably for legacy reasons). System.Net.ServicePointManager.SecurityProtocol is set to only accept Ssl3 and Tls (meaning Tls 1.0)

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