We generated the following link for the user Imagine&Engage for the CentralAuth URL: https://meta.wikimedia.org/w/index.php?title=Special%3ACentralAuth&target=Imagine&Engage. This doesn't work correctly, showing information for the user 'Imagine'. Likewise for the Global User Contributions tool: https://tools.wmflabs.org/guc/?user=Imagine&Engage.
We should instead be creating the URL https://meta.wikimedia.org/w/index.php?title=Special%3ACentralAuth&target=Imagine%26Engage, with the & URL escaped to %26.
This likely applies to all the URLs generated as properties on the User model. See https://github.com/WikipediaLibrary/TWLight/blob/master/TWLight/users/models.py#L158 and below.
See https://www.urlencoder.io/python/#url-encoding-in-python-2x for information on how to escape URLs in Python 2.