Issue was caused when exec is tarted, exits, then stated again. In this case, `Close` is called twice, which closes a channel twice. Changes execConfig.ExitCode to a pointer so we can test if the it has been set or not. This allows us to return early when the exec has already been run. Signed-off-by: Brian Goff <cpuguy83@gmail.com> Upstream-commit: 1a60a805bfabee729dbc833515cd0be439adb95b Component: engine