String interpolation doesn't work with sys.version_info in Python versions in which sys.version_info is a named tuple. It's a regression in Python 2.7 and 3.1. This problem doesn't concern named tuples created using collections.namedtuple().

This problem might also concern sys.getwindowsversion(), but I don't have access to Windows system, so I can't check it.

$ python2.6 -c 'import sys; print("%s.%s.%s-%s-%s" % sys.version_info)'
2.6.5-final-0
$ python2.7 -c 'import sys; print("%s.%s.%s-%s-%s" % sys.version_info)'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
TypeError: not enough arguments for format string
$ python3.0 -c 'import sys; print("%s.%s.%s-%s-%s" % sys.version_info)'
3.0.1-final-0
$ python3.1 -c 'import sys; print("%s.%s.%s-%s-%s" % sys.version_info)'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
TypeError: not enough arguments for format string