<C-^> does not work if # register contains an absolute path

[lalexf]

Describe the bug
If you open a files outside of your working directory/ workspace you can not toggle between them using '<C-^>'.
The path in the registers '#' and '%' are correct but contain absolute paths. <C-^> does nothing.

To Reproduce
Steps to reproduce the behavior:

1. Open a file in your working directory
2. Open your settings.json at /Users/<username>/Library/Application Support/Code/User/settings.json (Mac OS)
3. Try to toggle between the files via <C-^> (or vim_ctrl_6)

Expected behavior
You can toggle between the files.

Environment (please complete the following information):

• Extension (VsCodeVim) version: v1.20.3
• VSCode version: 1.56.2
• OS: macOS Catalina