Tasks.json environment variable expansion case sensitive

[gregvanl]

• VSCode Version:0.10.13 alpha
• OS Version:Windows 10

Steps to Reproduce:

1. Add an variable to your tasks.json ex. ${env.PATH}
   "command": "echo",
   "isShellCommand": true,
   "args": ["${env.PATH}"],
2. Run the task.
   This will expand correctly on Linux and OS X but not Windows since the expansion is case sensitive and PATH on Windows is "Path".
   Env Var expansion shouldn't be case sensitive so that the same task can run on all platform.
   This bug was requested by @dbaeumer in vscode-docs issue tasks.json documentation innacurate? vscode-docs#247

[dbaeumer]

@isidorn this is done by the resolver service. IMO env variables on all OSes are case insensitive. Should we address this.

[isidorn]

Let's keep it open and if some user is passionate he can tackle it
Code pointer

[weinand]

On linux and macOS environment variables are case sensitive, so "Path" and "PATH" are different variables on linux and macOS (but not on Windows). So your statement from above "IMO env variables on all OSes are case insensitive." is not correct, right?

@dbaeumer so you are asking for making env var lookup case insensitive on Windows only, correct?

[dbaeumer]

I thought they are always case insensitive. So it should be case insensitive then on Windows only

[heaths]

@isidorn, I'm actually about done with a change for this if you want to take a look.

[isidorn]

@heaths thanks, I will review the PR.

[heaths]

@isidorn did you want me to squash it or anything (fixed a broken test because I forgot the existing code returned an empty string for missing environment variables)? Different projects have different requirements and I didn't see anything about squashing in your contrib docs.

[isidorn]

@heaths no need to squash, I will add the comments to the PR directly if something is needed. Thanks