Prefer specific alias over wildcard, regardless of case

Since direct addresses (not aliases) are case-insensitive since a while,
it makes sense for aliases to behave the same. Up until now, a wildcard
alias could trump a alias not-matching-the-case of the incoming address.
This clarifies this behavior.

closes #1387

core/admin/mailu/models.py

@@ -451,25 +451,34 @@ class Alias(Base, Email):
                     )
                 )
             ).order_by(cls.wildcard, sqlalchemy.func.char_length(cls.localpart).desc()).first()
-        if alias_preserve_case:
-            return alias_preserve_case
 
-        if localpart:
-            localpart = localpart.lower()
-        return cls.query.filter(
+        localpart_lower = localpart.lower() if localpart else None
+        alias_lower_case = cls.query.filter(
                 sqlalchemy.and_(cls.domain_name == domain_name,
                     sqlalchemy.or_(
                         sqlalchemy.and_(
                             cls.wildcard == False,
-                            sqlalchemy.func.lower(cls.localpart) == localpart
+                            sqlalchemy.func.lower(cls.localpart) == localpart_lower
                         ), sqlalchemy.and_(
                             cls.wildcard == True,
-                            sqlalchemy.bindparam("l", localpart).like(sqlalchemy.func.lower(cls.localpart))
+                            sqlalchemy.bindparam("l", localpart_lower).like(sqlalchemy.func.lower(cls.localpart))
                         )
                     )
                 )
             ).order_by(cls.wildcard, sqlalchemy.func.char_length(sqlalchemy.func.lower(cls.localpart)).desc()).first()
 
+        if alias_preserve_case and alias_lower_case:
+            if alias_preserve_case.wildcard:
+                return alias_lower_case
+            else:
+                return alias_preserve_case
+        elif alias_preserve_case and not alias_lower_case:
+            return alias_preserve_case
+        elif alias_lower_case and not alias_preserve_case:
+            return alias_lower_case
+        else:
+            return None
+
 class Token(Base):
     """ A token is an application password for a given user.
     """

towncrier/newsfragments/1387.bug

@@ -0,0 +1 @@
+Fix alias resolution in regard to case: A specifically matching alias of wrong case is now preferred over a wildcard alias that might have »eaten« it previously.