path/filepath: in Rel use case-insensitive comparison on Windows

Fixes #10802

Compare Volume name and each path elements using strings.EqualFold.

Change-Id: Ibdefdb801d0326e53755bc9cc8c10eed998094e5
Reviewed-on: https://go-review.googlesource.com/16795
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/path/filepath/path_plan9.go b/src/path/filepath/path_plan9.go
index 962774efd5..60d46d9d42 100644
--- a/src/path/filepath/path_plan9.go
+++ b/src/path/filepath/path_plan9.go
@@ -42,3 +42,7 @@ func join(elem []string) string {
 	}
 	return ""
 }
+
+func sameWord(a, b string) bool {
+	return a == b
+}