Subscribing to notes emails fails for users with '@' symbols in the username

Steps to reproduce:

Login to BioPortal with an account where the username contains an '@' symbol
Navigate to the Notes page for any ontology, e.g., https://bioportal.bioontology.org/ontologies/HRAVS?p=notes
Click the "Subscribe to notes emails" button

User is presented with "Problem subscribing to emails, please try again" error message.

Underlying stack trace:

Processing by SubscriptionsController#create as JSON
  Parameters: {"user_id"=>"https://stagedata.bioontology.org/users/jvendetti@yahoo.com", "ontology_id"=>"HRAVS", "subbed"=>"false"}
Completed 500 Internal Server Error in 439676ms (Allocations: 2628555)

Exception (Exception):

app/controllers/subscriptions_controller.rb:7:in `create'

The user_id parameter is coming in unencoded.

ncbo / bioportal_web_ui

Subscribing to notes emails fails for users with '@' symbols in the username #300