Auto-update on Windows fails on default MSI options when executed from Core-based PSIC

[joeyaiello]

System Details

System Details Output

### VSCode version: 1.39.2 6ab598523be7a800d7f3eb4d92d7ab9a66069390 x64

### VSCode extensions:
akamud.vscode-theme-onelight@2.1.0
ban.spellright@3.0.48
blackmist.LinkCheckMD@0.1.5
cssho.vscode-svgviewer@2.0.0
darkriszty.markdown-table-prettify@2.4.0
DavidAnson.vscode-markdownlint@0.32.0
dbaeumer.vscode-eslint@1.9.1
docsmsft.docs-article-templates@0.2.7
docsmsft.docs-authoring-pack@0.1.3
docsmsft.docs-markdown@0.2.25
docsmsft.docs-metadata@1.0.0
docsmsft.docs-preview@0.3.35
docsmsft.docs-yaml@0.2.4
DotJoshJohnson.xml@2.5.0
DougFinke.vscode-pandoc@0.0.8
eamodio.gitlens@10.2.0
GitHub.vscode-pull-request-github@0.12.0
jock.svg@1.0.5
monokai.theme-monokai-pro-vscode@1.1.14
ms-azuretools.vscode-azurefunctions@0.20.0
ms-vscode.azure-account@0.8.7
ms-vscode.csharp@1.21.7
ms-vscode.powershell@2019.11.0
ms-vscode.powershell-preview@2019.11.0
msazurermtools.azurerm-vscode-tools@0.8.2
PKief.material-icon-theme@3.9.1
redhat.vscode-yaml@0.6.1
streetsidesoftware.code-spell-checker@1.7.20
tht13.html-preview-vscode@0.2.5
vscodevim.vim@1.11.3
yiwwan.vscode-scope@0.0.21
zhuangtongfa.Material-theme@2.28.3


### PSES version: 2.0.0.0

### PowerShell version:

Name                           Value
----                           -----
PSVersion                      7.0.0-preview.6
PSEdition                      Core
GitCommitId                    7.0.0-preview.6
OS                             Microsoft Windows 10.0.19508
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Issue Description

1. Got the update notification for preview.6 while sitting in a preview.5 PSIC.
2. Confirmed no other pwsh was running.
3. Clicked yes on the update notification.
   • Confirmed that the PSIC was synchronously blocked on execution of the MSI.
4. Clicked through the MSI with default options
5. Got the dialog complaining that a pwsh is still open, and so the installer can't proceed.
6. Left the radio box selected that closes all pwsh instances and attempts to restart them.
   • As opposed to the one that finishes install on restart.
7. The PSIC pwsh gets terminated by the MSI, and the MSI gets terminated because it's a child process of pwsh.
8. When the PSIC restarts, it spews an error about broken pipelines (presumably because the PowerShell install is now in a half-way broken state having been terminated abruptly).

Expected Behavior

Clicking Yes -> Next -> Next -> Next etc. should update you to the latest version of PowerShell on Windows.

Not sure if this problem is happening on other platforms, but this could be fixed on Windows by automatically setting the PSIC to Windows PowerShell 5.1 before proceeding with the install script. (Though I guess this wouldn't work in future versions of the extension where 3.0 and 4.0 aren't supported.....it could drop the PSIC altogether and run the script in a PATH'd powershell.exe terminal instance.)

Actual Behavior

The MSI process is ended abruptly, and I'm left with a corrupted, partial update of PowerShell.

Attached Logs

I have these handy, but I don't want to scrub them right now, and I think the busted behavior is clear. If you really need 'em, let me know.

[SydneyhSmith]

@joeyaiello thanks for opening this issue and providing detailed system information and repro steps! We are looking into resolving this issue and will let you know if we need more log information--thanks!