Group auto-fill: don't re-use users of other groups

[ywarnier]

Current behavior

When creating several groups in a course and using the auto-fill bucket, the same users are selected each time.

Expected behavior

For the second group, the auto-fill feature should only select users that are not already part of any other group.

Steps to reproduce

• Create a course
• Subscribe 10 users to course
• Create 3 groups of 2 users
• Click the "auto-fill" bucket for group 1
• Click the "auto-fill" bucket for group 2
• The members of group 2 are the same as the ones of group 1

Chamilo Version

1.11.x 20180430

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ywarnier]

Additional info: there's an option in the groups configuration allowing to decide whether a user can be subscribed to more than one group. I believe this option would have a better default value if it was set to "no" (do not allow users to be in several groups) and then the auto-fill should check that value before filling.