ReleaseRWLayer can and should only be called once (unless it returns
an error), but might be called twice in case of a failure from
`system.EnsureRemoveAll(container.Root)`. This results in the
following error:
> Error response from daemon: driver "XXX" failed to remove root filesystem for YYY: layer not retained
The obvious fix is to set container.RWLayer to nil as soon as
ReleaseRWLayer() succeeds.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit e9b9e4ace294230c6b8eb010eda564a2541c4564)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
deff200c90