Fix pattern with slash in range (#55)

When a slash appears in a range, it should NOT match a directory
separator.

Quoting https://git-scm.com/docs/gitignore#_pattern_format:

  The range notation, e.g. [a-zA-Z], can be used to match one of the
  characters in a range. See fnmatch(3) and the FNM_PATHNAME flag for
  a more detailed description.

And quoting what fnmatch(3) has to say about FNM_PATHNAME:

  match a slash in string only with a slash in pattern and not by an
  asterisk (*) or a question mark (?) metacharacter, nor by a bracket
  expression ([]) containing a slash.

Hence, it seems to me that a slash inside a range should be disregarded.

gitignore_parser.py

@@ -193,7 +193,7 @@ def fnmatch_pathname_to_regex(
             if j >= n:
                 res.append('\\[')
             else:
-                stuff = pattern[i:j].replace('\\', '\\\\')
+                stuff = pattern[i:j].replace('\\', '\\\\').replace('/', '')
                 i = j + 1
                 if stuff[0] == '!':
                     stuff = ''.join(['^', stuff[1:]])

tests.py

@@ -135,6 +135,15 @@ def test_supports_path_type_argument(self):
         self.assertTrue(matches(Path('/home/michael/file1')))
         self.assertFalse(matches(Path('/home/michael/file2')))
 
+    def test_slash_in_range_does_not_match_dirs(self):
+        matches = _parse_gitignore_string('abc[X-Z/]def', fake_base_dir='/home/michael')
+        self.assertFalse(matches('/home/michael/abcdef'))
+        self.assertTrue(matches('/home/michael/abcXdef'))
+        self.assertTrue(matches('/home/michael/abcYdef'))
+        self.assertTrue(matches('/home/michael/abcZdef'))
+        self.assertFalse(matches('/home/michael/abc/def'))
+        self.assertFalse(matches('/home/michael/abcXYZdef'))
+
 def _parse_gitignore_string(data: str, fake_base_dir: str = None):
     with patch('builtins.open', mock_open(read_data=data)):
         success = parse_gitignore(f'{fake_base_dir}/.gitignore', fake_base_dir)