Fix version number recognition heuristics
The regexp was wrong, for example it matched "2.20x" but failed to
match "3.1".
Some test cases:
>>> def f(title):
... version_number = re.search(_version_number_re, title)
... if version_number:
... return not re.search(_incomplete_version_number_re,
... version_number.group(0))
... else:
... return False
...
>>> [(s, f(s.encode('ascii'))) for s in ['foo', 'foo 3', 'foo 3.', 'foo 3.1', 'foo 3.14', 'foo 3.2.1', 'foo 3.2.1alpha', 'foo 3.1.a', 'foo 3.a', 'foo 3.x.1']]
[('foo', False), ('foo 3', False), ('foo 3.', False), ('foo 3.1', True), ('foo 3.14', True), ('foo 3.2.1', True), ('foo 3.2.1alpha', True), ('foo 3.1.a', False), ('foo 3.a', False), ('foo 3.x.1', False)]
afc9db8bb7