Revert "DeckManager: _checkDeckTree ignore case"

This reverts commit 9955048aec.

This commit broke collections that had children under each of the
the duplicate names - it renames one of the decks, but the children
of the renamed deck are left without a parent, causing an error like

line 235, in deckDueList  nlim = min(nlim, lims[p][0])\n\nKeyError('..)

Rather than a more complicated approach, I think it's safer just to
leave the case or normalization-differing decks around for now, and
we can normalize things properly in a future schema upgrade.

anki/decks.py

@@ -459,7 +459,7 @@ class DeckManager:
 
         for deck in decks:
             # two decks with the same name?
-            if self.normalizeName(deck['name']) in names:
+            if deck['name'] in names:
                 self.col.log("fix duplicate deck name", deck['name'])
                 deck['name'] += "%d" % intTime(1000)
                 self.save(deck)
@@ -473,12 +473,12 @@ class DeckManager:
             # immediate parent must exist
             if "::" in deck['name']:
                 immediateParent = "::".join(deck['name'].split("::")[:-1])
-                if self.normalizeName(immediateParent) not in names:
+                if immediateParent not in names:
                     self.col.log("fix deck with missing parent", deck['name'])
                     self._ensureParents(deck['name'])
-                    names.add(self.normalizeName(immediateParent))
+                    names.add(immediateParent)
 
-            names.add(self.normalizeName(deck['name']))
+            names.add(deck['name'])
 
     def checkIntegrity(self):
         self._recoverOrphans()