You’re getting System.String[] back because we’re actually runnng Python for .NET, and we’re not converting the string array to a python list when we give it back to you. This is really similar to what happened in Issue with SlaveExtraInfoDictionary
To get around it, you’ll have to iterate through that collection like this:
from Deadline.Scripting import RepositoryUtils
def __main__():
user = "jusbla"
user_groups = RepositoryUtils.GetUserGroupsForUser(user)
for group in user_groups:
print(group)