Remove current_app and current_user usage in forms.

app/auth/__init__.py

@@ -1,5 +1,8 @@
 from flask import Blueprint
 
 
+USERNAME_REGEX = '^[A-Za-zÄÖÜäöüß0-9_.]*$'
+
+
 bp = Blueprint('auth', __name__)
 from . import routes

app/auth/forms.py

@@ -1,4 +1,4 @@
-from flask import current_app
+from . import USERNAME_REGEX
 from ..models import User
 from flask_wtf import FlaskForm
 from wtforms import (BooleanField, PasswordField, StringField, SubmitField,
@@ -18,7 +18,7 @@ class RegistrationForm(FlaskForm):
     username = StringField(
         'Username',
         validators=[DataRequired(), Length(1, 64),
-                    Regexp(current_app.config['NOPAQUE_USERNAME_REGEX'],
+                    Regexp(USERNAME_REGEX,
                            message='Usernames must have only letters, numbers,'
                                    ' dots or underscores')]
     )