FIX: Interpret "ver+extra" as post-release, not pre-release

Author: effigies

nibabel/pkg_info.py

@@ -55,6 +55,10 @@ def cmp_pkg_version(version_str, pkg_version_str=__version__):
     pkg_version, pkg_extra = _parse_version(pkg_version_str)
     if version != pkg_version:
         return _cmp(StrictVersion(version), StrictVersion(pkg_version))
+    if extra.startswith('+') or pkg_extra.startswith('+'):
+        return (1 if pkg_extra == ''
+                else -1 if extra == ''
+                else _cmp(extra, pkg_extra))
     return (0 if extra == pkg_extra
             else 1 if extra == ''
             else -1 if pkg_extra == ''

nibabel/tests/test_pkg_info.py

@@ -63,6 +63,8 @@ def test_cmp_pkg_version():
                                        ('1.2.1rc', '1.2.1rc1', -1),
                                        ('1.2.1b', '1.2.1a', 1),
                                        ('1.2.1a', '1.2.1b', -1),
+                                       ('1.2.1+1', '1.2.1', 1),
+                                       ('1.2.1', '1.2.1+1', -1),
                                       ):
         assert_equal(cmp_pkg_version(test_ver, pkg_ver), exp_out)
     assert_raises(ValueError, cmp_pkg_version, 'foo.2')