Environment

• Ruby 2.6.1
• Rails 5.2.2
• Devise 4.6.1

Current behavior

It appears that PR #4261 introduced a change where encrypted_password could be set to nil even when no attempt was made to change password. The relevant comment is here #4261 (comment)

This results in user model forms that have a password field in activeadmin to break with a validation failure when the password field remains empty on submit:

ActiveRecord::NotNullViolation (PG::NotNullViolation: ERROR:  null value in column "encrypted_password" violates not-null constraint

Expected behavior

No attempt should be made to set encrypted_password to nil if the password field doesn't have a value. This was the case in devise versions prior to v4.6.0.