Cannot delete institution with CSV created groups

[Stacey Walker]

This is similar too but not a direct copy of: https://bugs.launchpad.net/bugs/1607231

Mahara: 16.04.3
DB: Postgres
OS: Linux
Browser: Firefox

A site admin user is not able to delete an institution when groups have been uploaded via CSV.

This appears to be because the groups have been uploaded with one or more foreign key references to the institution selected.

There is no reference within the UI to this though, so we cannot change the groups stored institution or delete only groups that are related so that we can delete the institution itself.

This is a rather large blocker to deleting obsolete information within any configuration.

To reproduce:
1. Create a custom institution
2. Upload a CSV of groups
3. Try to delete institution

This looks most problematic if you have more than one institution and groups created both manually and via CSV as you cannot distinguish easily. Also, you cannot link an institution via the manual creation it seems.

[Robert Lyon (robertl-9)]

Hmm, this commit c019bd2e196d03eb5d9eb1177cde2ece2158a1c5 should deal with that problem.

I'll have to investigate some more as to why that would fail

[Robert Lyon (robertl-9)]

Unable to replicate so will need more info

[Launchpad Janitor (janitor)]

[Expired for Mahara because there has been no activity for 60 days.]