Update git submodules

* Update cliff from branch 'master'
  to a5bdcc6e789adb0182df0721909d7b657f9a50b5
  - Merge "Handle null values when sorting"
  - Handle null values when sorting
    
    One unfortunate change (or fortunate, depending on how you look at
    types) in Python 3 is the inability to sort iterables of different
    types. For example:
    
      >>> x = ['foo', 'bar', None, 'qux']
      >>> sorted(x)
      Traceback (most recent call last):
        File "<stdin>", line 1, in <module>
      TypeError: '<' not supported between instances of 'NoneType' and 'str'
    
    Fortunately, we can take advantage of the fact that by providing a
    function for the 'key' that returns a tuple, we can sort on multiple
    conditions. In this case, "when the first key returns that two elements
    are equal, the second key is used to compare." [1] We can use this to
    first separate the values by whether they are None or not, punting those
    that are not to the end, before sorting the non-None values normally.
    For example:
    
      >>> x = ['foo', 'bar', None, 'qux']
      >>> sorted(x, key=lambda k: (k is None, k))
      ['bar', 'foo', 'qux', None]
    
    We were already using this feature implicitly through our use of
    'operator.itemgetter(*indexes)', which will return a tuple if there is
    more than one item in 'indexes', and now we simply make that explicit,
    fixing the case where we're attempting to compare a comparable type
    with None. For all other cases, such as comparing a value that isn't
    comparable, we surround things with a try-catch and a debug logging
    statement to allow things to continue.
    
    Note that we could optimize what we're done further by building a key
    value that covers all indexes, rather than using a for loop to do so.
    For example:
    
      >>> x = [('baz', 2), (None, 0), ('bar', 3), ('baz', 4), ('qux', 0)]
      >>> sorted(x, key=lambda k: list(
      ...     itertools.chain((k[i] is None, k[i]) for i in (0, 1)))
      ... )
      [('bar', 3), ('baz', 2), ('baz', 4), ('qux', 0), (None, 0)]
    
    However, this would be harder to grok and would also mean we're unable
    to handle exceptions on a single column where e.g. there are mixed types
    or types that are not comparable while still sorting on the other
    columns. Perhaps this would be desirable for some users, but sorting on
    a best-effort basis does seem wiser and generally more user friendly.
    Anyone that wants to sort on such columns should ensure their types are
    comparable or implement their own sorting implementation.
    
    [1] https://www.kite.com/python/answers/how-to-sort-by-two-keys-in-python
    
    Change-Id: I4803051a6dd05c143a15923254af97e32cd39693
    Signed-off-by: Stephen Finucane <sfinucan@redhat.com>
    Story: 2008456
    Task: 41466

cliff

@@ -1 +1 @@
-Subproject commit fca202dfb2e22d88f95e0bcce848ec4839f745cf
+Subproject commit a5bdcc6e789adb0182df0721909d7b657f9a50b5