Fix incorrect or inconsistent slug generation.

Only scummvm uses "lutris_slug" but it is provided for Gog too - with stale data.

lutris/services/amazon.py

@@ -641,10 +641,6 @@ class AmazonService(OnlineService):
         return [file_collection], []
 
     def get_installed_slug(self, db_game):
-        slug = db_game.get("lutris_slug")
-        if slug:
-            return slug
-
         details = json.loads(db_game["details"])
         return slugify(details["product"]["title"])
 

lutris/services/base.py

@@ -263,8 +263,8 @@ class BaseService(GObject.Object):
     def get_installed_slug(self, db_game):
         """Returns the slug the game will have after installation, by default. This
         is Lutris's slug, not the one for the service. By default, we derive it from
-        the Game's name, but services override this if they provide the slug."""
-        return db_game.get("lutris_slug") or slugify(db_game["name"])
+        the Game's name."""
+        return slugify(db_game["name"])
 
     def get_installed_runner_name(self, db_game):
         """Returns the name of the runner this game will have after installation, or

lutris/services/battlenet.py

@@ -156,7 +156,7 @@ class BattleNetService(BaseService):
         return slug
 
     def get_installed_slug(self, db_game):
-        return db_game.get("lutris_slug") or db_game["slug"]
+        return db_game["slug"]
 
     def generate_installer(self, db_game, egs_db_game):
         egs_game = Game(egs_db_game["id"])

lutris/services/itchio.py

@@ -328,7 +328,7 @@ class ItchIoService(OnlineService):
         return all_extras
 
     def get_installed_slug(self, db_game):
-        return db_game.get("lutris_slug") or db_game["slug"]
+        return db_game["slug"]
 
     def generate_installer(self, db_game):
         """Auto generate installer for itch.io game"""

lutris/services/scummvm.py

@@ -71,6 +71,9 @@ class ScummvmService(BaseService):
             }
         }
 
+    def get_installed_slug(self, db_game):
+        return db_game.get("lutris_slug") or slugify(db_game["name"])
+
     def get_installed_runner_name(self, db_game):
         return "scummvm"