"git push --recurse-submodules" learns to optionally look into the
histories of submodules bound to the superproject and push them out.
By Heiko Voigt
* hv/submodule-recurse-push:
push: teach --recurse-submodules the on-demand option
Refactor submodule push check to use string list instead of integer
Teach revision walking machinery to walk multiple times sequencially