Can't add new group members via a CSV file

[Son Nguyen]

Version: master
Platform: all
Browser: all

Assumptions
 - user 'u01' is an admin of institution 'S'
 - user 'u02' is a member of institution 'S'
 - user 'u01' created group 'A'
 - group 'A' was created by a csv, otherwise bug #826649 happens
 - A CSV file called gm.csv with the content:
shortname,username,role
"A","u02","member"

Actions
 - user 'u01' tried to update group members of group 'A' using the CSV file gm.csv.

Results
 - Error message: 'Error on line 2 of your file: The group shortname "A" did not have any users with the "admin" role specified.'

[Melissa Draper (melissa)]

After discussing this with hugh, I've concluded that this is behaving as per what is desccribed in the manual:

http://manual.mahara.org/en/1.6/site_admin/groups.html#update-group-members-by-csv

"If you manually added users to a group whose members you want to update via CSV file, these users will be removed from that group when you update the group membership and do not have them listed in the CSV file. Thus, be careful once you have added users manually."

So what's happening with the example provided is that because the original admin hasn't been listed in the csv, it's being removed, and hence the group would otherwise have no admin and this would make it broken, so it doesn't let it happen.