Steps to reproduce

1. Install extension from Marketplace
2. Execute "start Git mergetool"
3. Open view merge, but not the layout 4-ways or 3-ways

Expected behavior

Open the file in 4-ways merge

[Optional] screenshots

Environment

• Version of the extension: 0.14.0 - 2021-04-07
• Operating system: VSCode in windows, git in linux
• VS Code version [use Code command “Help: About”]: 1.63.2
• Other installed extensions (if applicable):

Additional context

The configuration of .gitconfig is:
[init]
templatedir = /home/xxx/.git-templates
[difftool "vscode"]
cmd = code --wait --diff $LOCAL $REMOTE
[merge]
tool = vscode
conflictstyle = zdiff3 (I probe with diff3 also)
[mergetool "vscode"]
cmd = code --wait $MERGED
[diff]
tool = vscode
[mergetool]
keepTemporaries = false
keepBackup = false

When I try to change the layout I see this message:
This requires the diff layout to be active