Merge branch 'pb/recurse-submodule-in-worktree-fix'

The "--recurse-submodules" option of various subcommands did not work well when run in an alternate worktree, which has been corrected. * pb/recurse-submodule-in-worktree-fix: submodule.c: use get_git_dir() instead of get_git_common_dir() t2405: clarify test descriptions and simplify test t2405: use git -C and test_commit -C instead of subshells t7410: rename to t2405-worktree-submodule.sh