Prevent a potential race when stopping containers

If sending a signal fails, check if the container is alive. If it
is not, it probably stopped on its own before we could send the
signal, so don't error out.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #591
Approved by: rhatdan
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f