With `rprivate` there exists a race where a reference to a mount has
propagated to the new namespace, when `rprivate` is set the parent
namespace is not able to remove the mount due to that reference.
With `rslave` unmounts will propagate correctly into the namespace and
prevent the sort of transient errors that are possible with `rprivate`.
This is a similar fix to 117c92745b
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Upstream-commit: 5ede64d63fec0b9d4cf921b6f8fb946e65287538
Component: engine
3c89b7fafe