Comment 10 for bug 1783978

I have created a minimal reproducer: https://gist.github.com/yoctozepto/e6fdc2789297fdfdff4fd45fe64c9cb9

And found that the issue was already observed, albeit for a different reason: https://github.com/moby/moby/issues/35323

It seems docker treats cases (2) and (4) differently and for some reason preserves the "shared" submounts and then forcibly mounts again on container start which causes the exponential growth effect.