**What did you do?**

**What did you expect to see?**

**What did you see instead? Under which circumstances?**

**Environment**

* System information:

	insert output of `uname -srm` here

* Prometheus version: 

	insert output of `prometheus -version` here

* Alertmanager version:

	insert output of `alertmanager -version` here (if relevant to the issue)

* Prometheus configuration file:
```
insert configuration here
```

* Alertmanager configuration file:
```
insert configuration here (if relevant to the issue)
```

* Logs:
```
insert Prometheus and Alertmanager logs relevant to the issue here
```
