How can signal handlers be made branch-aware?

[peteeckel]

Hi, I'm maintaining a plugin that, among other things, uses an m2m_changed handler for some parts of its functionality, and that handler issues write operations to the database.

As far as I know I need to make those write operations branch-aware. How can I determine the current branch in a signal handler? Is there some way to find the branch a specific request (i.e. found by the current_request method) is tied to a branch?