On case-insensitive file systems, the editor may send us a path that
works but doesn't match the actual file's case. Then when we run go
list, we'll get mismatching paths and everything will break.
We can't reliably fix this problem: tracking what case the editor
expects is too difficult to be worth it. Instead, check the workspace
path and bail if it's mismatched.
Possibly we should also check files on DidOpen or such, but we can start
with this.
Updates golang/go#36904.
Change-Id: I7635c8136bf9400db4143a0f2fde25c39b5abc44
Reviewed-on: https://go-review.googlesource.com/c/tools/+/225239
Reviewed-by: Ian Cottrell <iancottrell@google.com>