NPE related to ContentGroups after editing Contents

This might have been introduced by !94 (merged).

@tksl38

I'll have a look at this tomorrow.

This is due to #30 (closed) : The old mobile client uses the information from the content GET request to build it's PUT (update). Since the group isn't emitted and therefore not parsed into the PUT which overrides the group(s) the content is currently in to an empty set.

mentioned in commit be571bb7

mentioned in merge request !106 (merged)

assigned to @dgrh99

mentioned in commit 6987618d

closed via commit be571bb7

closed via merge request !106 (merged)