Only 32-bits is presented to the user in the drop down menu

if the user uses a 32 bit OS (as a 32 bit OS can't run a 64-
bit OS), otherwise both the options are shown.

gui/mozregui/wizard.py

@@ -61,12 +61,13 @@ def __init__(self):
         self.ui.app_combo.setModel(self.app_model)
         self.bisect_model = QStringListModel()
         self.ui.bisect_combo.setModel(self.bisect_model)
-        self.bits_model = QStringListModel(['32', '64'])
-        self.ui.bits_combo.setModel(self.bits_model)
         if mozinfo.bits == 64:
+            self.bits_model = QStringListModel(['32', '64'])
             bits_index = 1
         elif mozinfo.bits == 32:
+            self.bits_model = QStringListModel(['32'])
             bits_index = 0
+        self.ui.bits_combo.setModel(self.bits_model)
         self.ui.bits_combo.setCurrentIndex(bits_index)
 
         self.ui.app_combo.currentIndexChanged.connect(self._set_fetch_config)