Made normpath('/.') and normpath('/..') behave more consistently

fs/path.py

@@ -46,7 +46,8 @@ def normpath(path):
     if not _requires_normalization(path):
         return path.rstrip('/')
 
-    components = [''] if path.startswith('/') else []
+    prefix = u'/' if path.startswith('/') else u''
+    components = []
     append = components.append
     special = ('..', '.', '').__contains__
     try:
@@ -61,7 +62,7 @@ def normpath(path):
         # causing a circular import.
         from fs.errors import BackReferenceError
         raise BackReferenceError('Too many backrefs in \'%s\'' % path)
-    return u'/'.join(components)
+    return prefix + u'/'.join(components)
 
 
 if os.sep != '/':

fs/tests/test_path.py

@@ -18,6 +18,7 @@ class TestPathFunctions(unittest.TestCase):
                     (".", ""),
                     ("./", ""),
                     ("", ""),
+                    ("/.", "/"),
                     ("/a/b/c", "/a/b/c"),
                     ("a/b/c", "a/b/c"),
                     ("a/b/../c/", "a/c"),
@@ -50,7 +51,9 @@ class TestPathFunctions(unittest.TestCase):
             result = testpaths[-1]
             self.assertEqual(pathjoin(*paths), result)
 
+        self.assertRaises(ValueError, pathjoin, "..")
         self.assertRaises(ValueError, pathjoin, "../")
+        self.assertRaises(ValueError, pathjoin, "/..")
         self.assertRaises(ValueError, pathjoin, "./../")
         self.assertRaises(ValueError, pathjoin, "a/b", "../../..")
         self.assertRaises(ValueError, pathjoin, "a/b/../../../d")