Containers: Git credentials helper for external shells

• VSCode Version: 1.52
• Local OS Version: Windows 10
• Remote OS Version: Ubuntu 20.04
• Remote Extension/Connection Type: Docker/WSL

I have Windows 10 with Docker for Windows, WSL 2 and the docker engine is integrated into the WSL2.
The devcontainer is a Ubuntu 20.04 based image.

In the WSL I configured git according to https://docs.microsoft.com/en-us/windows/wsl/tutorials/wsl-git (git credential manager setup).
In the running devcontainer git works.
In the devcontainer's bash shell it does not. On every git command it says
Remote-Containers CLI: RPC pipe not configured. Message: {"command":"fill","stdin":"protocol=https\nhost=bitbucket.org\nusername=fhuonder\n"}

In the devcontainer's bash the git config for the credential helper looks like
credential.helper=!f() { /root/.vscode-server/bin/940b5f4bb5fa47866a54529ed759d95d09ee80be/node /tmp/vscode-remote-containers-f71604cb655ae555002aed74e1d2d934ff7f5afe.js $*; }; f

Any hints?
I already searched to issues but only found similar issue but not exactly the same.

Regards,
Florian