Make sure not to catch keyboard interrupts and system exits

scripts/effectUsedBy.py

@@ -119,7 +119,7 @@ def calc_outerscore(innerscore_dict, pereffect_totalaffected, weight):
 def validate_string(s):
     try:
         s.encode('ascii')
-    except KeyboardInterrupt:
+    except (KeyboardInterrupt, SystemExit):
         raise
     except Exception:
         return False

scripts/itemDiff.py

@@ -394,6 +394,8 @@ def main(old, new, groups=True, effects=True, attributes=True, renames=True):
         new_cursor.execute(query)
         for row in new_cursor:
             new_meta[row[0]] = row[1]
+    except (KeyboardInterrupt, SystemExit):
+        raise
     except:
         pass
     # Print jobs