[rush] Let's document best practices for WSL + Rush

[octogonz]

Relatively few people are using Windows Subsystem for Linux (WSL) with Rush.

In a recent Zulip thread, @Akres encountered some problems where Rush's incremental builds were not calculated correctly:

The incremental build feature works, but sometimes triggers a full rebuild while nothing has changed. That wouldn't be so bad. The flip side of the same issue is that when there is a change, the package sometimes does not rebuild, which makes it largely unusable.

I have done a bit of digging and found that the issue happens in https://github.com/microsoft/rushstack/blob/main/libraries/package-deps-hash/src/getRepoState.ts#L309 getRepoStateAsync

I did some debugging and found that the git status call quite frequently (about 50% of times, for me) returns an empty output, so the hashes, which this function returns, are that of the repo in its unmodified state.

I was pointed in this direction by https://stackoverflow.com/a/55692650 this comment. It seems that the issue really comes from two git commands running simultaneously, because when I tried to play with the code that I have locally and I serialized the calls, the issue disappeared.

Reply to this thread with any wisdom, recommendations, or workarounds for WSL+Rush. Then we can write up a website documentation page providing guidance for best practices with WSL.