Backport:

Backport:
- Patch #1400181, fix unicode string formatting to not use the locale.
  This is how string objects work.  u'%f' could use , instead of .
  for the decimal point.  Now both strings and unicode always use periods.

This is the code that would break:

    import locale
    locale.setlocale(locale.LC_NUMERIC, 'de_DE')
    u'%.1f' % 1.0
    assert '1.0' == u'%.1f' % 1.0

I couldn't create a test case which fails, but this fixes the problem.
(tested in interpreter and reported fixed by others)