Merge branch 'sb/submodule-update-dot-branch'

A few updates to "git submodule update". Use of "| wc -l" break with BSD variant of 'wc'. * sb/submodule-update-dot-branch: t7406: fix breakage on OSX submodule update: allow '.' for branch value submodule--helper: add remote-branch helper submodule-config: keep configured branch around submodule--helper: fix usage string for relative-path submodule update: narrow scope of local variable submodule update: respect depth in subsequent fetches t7406: future proof tests with hard coded depth