The `ExecBackend.ContainerKill()` function was called before removing a build-
container.
This function is backed by `daemon.ContainerKill()` which, if no signal is passed,
performed a `daemon.Kill()`, using `SIGKILL` as signal. However, the
`ExecBackend.ContainerRm()` (backed by `daemonContainerRm()`), which is called
after this, is executed with the `ForceRemove` option set, which calls
`daemon.cleanupContainer()` with `ForceRemove` set, which also results in
`daemon.Kill()` being called:
1a0c15abbb/daemon/delete.go (L84-L95)
This makes the `ExecBackend.ContainerKill()` redundant, so removing this from
the interface.
While looking at this code, one (possible) race-condition was found in
`daemon.cleanupContainer()`, where `daemon.Kill()` could return a `errdefs.Conflict`
if the container was already stopped. An extra check was added for this case to
prevent `daemon.cleanupContainer()` from terminating early.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
1f9098e7d0