helm dependency upgrade wasn't working on certain file system because it assumes that os.rename is available. Since rename isn't available for subfolders in docker containers, I ripped a fallback rename strategy from dep (https://github.com/golang/dep/blob/5b1fe9e6d89372487d0aac78d9c5362a517857e7/internal/fs/fs.go#L103-L118) that works in docker.
Signed-off-by: Brice Rising <brice.rising@slalom.com>
(cherry picked from commit 94d87ef95db922c23ee9fff0a1808482635dcd6a)