Repository: vscode
Issue: Stuck while trying to install plugins in WSL using corporate proxy
Labels: bug,proxy,remote

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- VSCode Version: 1.46.1
- OS Version: Win10 2004
- Tried both using WSL1 and WSL2, both running Ubuntu 20.04

I'm running code behind a corporate network, have http_proxy and https_proxy (on both Windows and WSL set to the respective proxy server.
Internet access is both working for Windows (and plugin install, too) and from WSL side (except the code plugin installation.

Maybe I missed the instructions on how to operate visual studio code with WSL + proxy?

Steps to Reproduce:

1. Open vscode from WSL: `code .`
2. Try installing any of the already installed plugins into WSL, e.g. git lens
3. After clicking the button labelled 'Install in WSL: &lt;wsl name&gt;' mostly nothing happens. Sometimes the button text changes to 'Installing' for some time - however it will be then stuck there. There's no progress or error message in any case. 

I checked the local and remote extensions host log, too - with trace enabled:

For WSL1 the following entries could be found in the log:
```txt
[2020-06-29 18:25:53.882] [remoteagent] [trace] ExtensionManagementService.refreshReportedCache
[2020-06-29 18:25:53.882] [remoteagent] [trace] RequestService#request https://az764295.vo.msecnd.net/extensions/marketplace.json
[2020-06-29 18:26:29.562] [remoteagent] [trace] Started scanning system extensions
[2020-06-29 18:26:29.562] [remoteagent] [trace] Started scanning user extensions
[2020-06-29 18:26:29.564] [remoteagent] [trace] Scanned user extensions: 0
[2020-06-29 18:26:29.611] [remoteagent] [trace] {"errno":-2,"code":"ENOENT","syscall":"open","path":"/home/fooUser/.vscode-server/bin/cd9ea6488829f560dc949a8b2fb789f3cdc05f5d/extensions/node_modules/package.json"}
```

For WSL2 the same looked like:
```txt
[2020-06-29 18:24:31.296] [remoteagent] [trace] {"errno":-2,"code":"ENOENT","syscall":"open","path":"/root/.vscode-server/bin/cd9ea6488829f560dc949a8b2fb789f3cdc05f5d/extensions/node_modules/package.json"}
[2020-06-29 18:24:31.300] [remoteagent] [trace] Scanned system extensions: 30
[2020-06-29 18:24:43.700] [remoteagent] [trace] ExtensionManagementService.refreshReportedCache
[2020-06-29 18:24:43.701] [remoteagent] [trace] RequestService#request https://az764295.vo.msecnd.net/extensions/marketplace.json
[2020-06-29 18:29:13.672] [remoteagent] [trace] Started scanning user extensions
[2020-06-29 18:29:13.673] [remoteagent] [trace] Scanned user extensions: 0
[2020-06-29 18:31:04.845] [remoteagent] [trace] Started scanning system extensions
```

I checked the trace log after starting code using `--log=trace` - there seem to be some errors during the plugin discovery - however I'm not sure.

I attached a slightly modified version (replaced my user name - and left only the tail of the log) of the log.
[sharedprocess.log](https://github.com/microsoft/vscode/files/4846713/sharedprocess.log)


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