• VSCode Version: 1.5.3
• OS Version: Windows 10

Steps to Reproduce:

1. Create a new vscode extension as described on the official page
2. Write the following code in the extension.ts

var channel = vscode.window.createOutputChannel('test');
channel.show();

channel.append(path.join(vscode.workspace.rootPath, 'nospace', 'file.txt') + ':2:10\r\n');       

channel.append(path.join(vscode.workspace.rootPath, 'with space', 'file.txt') + ':2:10\r\n');    
channel.append(path.join(vscode.workspace.rootPath, 'with%20space', 'file.txt') + ':2:10\r\n');    
channel.append('"' + path.join(vscode.workspace.rootPath, 'with space', 'file.txt') + '"' + ':2:10\r\n');    
channel.append("'" + path.join(vscode.workspace.rootPath, 'with space', 'file.txt') + "'" + ':2:10\r\n');

1. Run the extension and open the folder with the following structure:
   myfolder
   -- with space
   ---- file.txt
   -- nospace
   ---- file.txt
2. Run "Hello world" command to trigger extension and expect the output

The first link to \nospace\file.txt:2:10 is correctly recognized and ctrl+click opens the file.
The rest of the links to \with space\file.txt:2:10 are not correctly parsed. Quoting to url escaping does not help.