* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code
#649
* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code
#649
* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code
#649
* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code
#649
* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code #649
* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code #649
* Make watchtower skip update if pre-update lifecycle hook exits with a non-zero exit code #649
* Prevent starting new container if old one is not stopped because of lifecycle hook.
* Add null check for c.containerInfo.State in IsRunning
* Fixed that the container would not start
* Added test for preupdate
* EX_TEMPFAIL -> ExTempFail
* Added missing fuction ouput names
* Skip preupdate when container is restarting.
The life-cycle messages should not have the same level as the update messages.
Why?
I receive a (mail-) notification for every run even if no image is changed:
```
2020-07-31 06:44:33 (info): Executing pre-check command.
```
But I only want to receive a notification if something changed:
```
2020-07-20 06:44:44 (info): Found new traefik:v2.2 image (sha256:7c992081f52423e325bd12debf0edcb4f7cfa398683c26f99c00112ec14e1ab9)
```
