Merge branch 'jl/maint-submodule-recurse-fetch' into maint

"git fetch" that recurses into submodules on demand did not check if it needs to go into submodules when non branches (most notably, tags) are fetched. By Jens Lehmann * jl/maint-submodule-recurse-fetch: submodules: recursive fetch also checks new tags for submodule commits