This is no new issue and most likely it will only be relevant to older rails projects, but since I faced the same issue again and meanwhile forgot what it was about and how it should be fixed, here a note to self.
For more details and an appropriate header image for this subject, check out Christine’s Post on this issue: What’s up with mimemagic breaking everything?
While running bundle install
In 2018 I wrote a quick post on how to flood phishing pages with a python script. Unfortunately that doesn’t work with python3 anymore and also doesn’t handle POST request, me not really being a python dev decided to use bash with two packages instead of coding something in ruby.
apt install pwgen gpw
That’s it for the packages, now you have something to generate usernames and passwords.
Looking at the page sources shows two fields being used, a field email and password.