Trying to add a user to a group that is already a member of the group
currently fails with 'Not Found'. If multiple users are added in bulk,
the users which are already a member of the group are ignored. Do the
same on adding a single user to a group. If the user is already a
member of the group do nothing, but also do not fail.
Change-Id: I644af9876c8488d9bf80d2c4bec3cbd75b2ffead
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
2cbbd293bb