[FS#965] flyspray: login is broken when github changes the email

[LEDE Bugs]

For full information about what has changed in this task, visit the URL below and click the History tab.

FS#965 - flyspray: login is broken when github changes the email
User who did this: Alexander Couzens (lynxis)
Summary: flyspray: registration via github is broken -> flyspray: login is broken when github changes the email
Task details edited:
-------
The user must already registered with the old email.
The user tries to login with the new email via github oauth, flysprays
rejects the user with "Error #23: User or group not enabled for login."
-------

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=965