I lost the original build file, but it is still there working nicely in the container. I would like to avoid rebuilding, as some edge conditions might come to play. I would expect it is possible to back up the working binary, so I could deploy new version and safely rollback if unfortunate. However, I can't find the folder where these are stored, or any commands that would magically extract the bundle.
There is a folder $FUSE_HOME/data/repository with a maven-like structure, and it seems to contain most of the installed bundles, but apparently not all, specifically not the version I am after.
Under the 'data/cache' directory you will see the bundles and the bundle numbers. Do a 'osgi:list' on the karaf shell and find the number of your bundle. Underneath the bundle+number directory you will find the deployed bundle creatively named 'bundle.jar'.