Incorrect behaviour with relative paths

[limexp]

There is an error in case of using relative paths: search with caseSensitive: true returns more results then caseSensitive: false.

Here is an example. Consider the following directories:

.
├── dir1
│   └── file1.txt
└── dir2
    └── file2.txt

Run the following program from the dir1:

import 'package:glob/glob.dart';
import 'package:glob/list_local_fs.dart';

void main(List<String> arguments) {
  print('1: ${Glob('**.txt', caseSensitive: null).listSync()}');
  print('2: ${Glob('**.txt', caseSensitive: false).listSync()}');
  print('3: ${Glob('**.txt', caseSensitive: true).listSync()}');

  print('4: ${Glob('../dir2/**.txt', caseSensitive: null).listSync()}');
  print('5: ${Glob('../dir2/**.txt', caseSensitive: false).listSync()}');
  print('6: ${Glob('../dir2/**.txt', caseSensitive: true).listSync()}');

  print('7: ${Glob('..\\dir2\\**.txt', caseSensitive: null).listSync()}');
  print('8: ${Glob('..\\dir2\\**.txt', caseSensitive: false).listSync()}');
  print('9: ${Glob('..\\dir2\\**.txt', caseSensitive: true).listSync()}');
}

Output on Linux:

1: [LocalFile: './file1.txt']
2: [LocalFile: './file1.txt']
3: [LocalFile: './file1.txt']
4: [LocalFile: './../dir2/file2.txt']
5: []
6: [LocalFile: './../dir2/file2.txt']
7: []
8: []
9: []

Output on Windows:

1: [LocalFile: '.\file1.txt']
2: [LocalFile: '.\file1.txt']
3: [LocalFile: '.\file1.txt']
4: []
5: []
6: [LocalFile: '.\..\dir2\file2.txt']
7: []
8: []
9: []

4 is OK, because caseSensitive defaults to false when context is Windows and true otherwise.

The real problem is that more strict condition caseSensitive: true (6) produces more then caseSensitive: false (5).