ostree 2017.7 incompatibility with flatpak < 0.9.6

[Alexander Larsson]

I noticed recently that the change to ostree:

https://github.com/ostreedev/ostree/commit/73ba3eb686ef86cea1c4563303e44df87d73e6c6

that makes ostree mirroring not mirror the summary file when doing a
partial mirror broke the systemwide install (as a user) of flatpak.
This is fixed in 0.9.6, so anyone who updates to the latest ostree
should also make sure that you update to the latest flatpak.