expand: environment variables are no longer case insensitive on Windows

[RossHammer]

When I run commands on my system I get the following when trying to run any exe

gosh -c "go version"
"go": executable file not found in $PATH
exit status 127

After doing some digging I noticed my path environment variable is Path not PATH for some reason. This is a relatively fresh install of windows as well. Once I changed it to PATH everything started working better

[mvdan]

Interesting - thanks for the report. We already do test on Windows via Travis, but as you can imagine, Windows environments can vary quite a lot.

I understand that environment variables in Windows are case insensitive, whereas they are case sensitive on unix-like systems. That is, os.Getenv("PATH") should succeed on Windows even if one has only set Path.

We used to take this into account when constructing an interpreter, but it seems like that piece of code was dropped recently. I can't think why I'd remove it, so I think it was just a mistake. I'll re-add it and add a regression test.

[mvdan]

@RossHammer could you please test a master build? I'm fairly positive that the commit above should fix it for you, but I'd like confirmation from you before doing a bugfix release.

[RossHammer]

That seems like it fixed it. Thanks