Observation summary reports commit of remote branch, not the upstream branch

[g7gpr]

In https://globalmeteornetwork.groups.io/g/coordinators/message/668 it was reported that the ObservationSummary does not report the upstream branch, but rather the source of the latest commit in the upstream branch.

Whilst this was as intended, it is only helpful for this purpose. Generally operators wish to know the upstream branch, and not the source of the latest commit on the upstream branch.

Change ObservationSummary to report the upstream branch.