Revert "submodule: explicit local branch creation in module_clone"

This reverts commit 23d25e48f5, as it is
broken for users who haven't opted into the new feature of checking
out submodule.*.branch with update mode set to checkout.

Documentation/git-submodule.txt

@@ -15,7 +15,7 @@ SYNOPSIS
 'git submodule' [--quiet] init [--] [<path>...]
 'git submodule' [--quiet] deinit [-f|--force] [--] <path>...
 'git submodule' [--quiet] update [--init] [--remote] [-N|--no-fetch]
-	      [-f|--force] [--checkout|--rebase|--merge] [--reference <repository>]
+	      [-f|--force] [--rebase|--merge] [--reference <repository>]
 	      [--depth <depth>] [--recursive] [--] [<path>...]
 'git submodule' [--quiet] summary [--cached|--files] [(-n|--summary-limit) <n>]
 	      [commit] [--] [<path>...]
@@ -155,31 +155,13 @@ it contains local modifications.
 
 update::
 	Update the registered submodules, i.e. clone missing submodules and
-	checkout the commit specified in the index of the containing
-	repository.  The update mode defaults to `checkout`, but can be
-	configured with the `submodule.<name>.update` setting or the
-	`--rebase`, `--merge`, or `--checkout` options.
-+
-For updates that clone missing submodules, checkout-mode updates will
-create submodules with detached HEADs; all other modes will create
-submodules with a local branch named after `submodule.<path>.branch`.
-+
-For updates that do not clone missing submodules, the submodule's HEAD
-is only touched when the remote reference does not match the
-submodule's HEAD (for none-mode updates, the submodule is never
-touched).  The remote reference is usually the gitlinked commit from
-the superproject's tree, but with `--remote` it is the upstream
-subproject's `submodule.<name>.branch`.  This remote reference is
-integrated with the submodule's HEAD using the specified update mode.
-For checkout-mode updates, that will result in a detached HEAD.  For
-rebase- and merge-mode updates, the commit referenced by the
-submodule's HEAD may change, but the symbolic reference will remain
-unchanged (i.e. checked-out branches will still be checked-out
-branches, and detached HEADs will still be detached HEADs).  If none
-of the builtin modes fit your needs, set `submodule.<name>.update` to
-`!command` to configure a custom integration command.  `command` can
-be any arbitrary shell command that takes a single argument, namely
-the sha1 to update to.
+	checkout the commit specified in the index of the containing repository.
+	This will make the submodules HEAD be detached unless `--rebase` or
+	`--merge` is specified or the key `submodule.$name.update` is set to
+	`rebase`, `merge` or `none`. `none` can be overridden by specifying
+	`--checkout`. Setting the key `submodule.$name.update` to `!command`
+	will cause `command` to be run. `command` can be any arbitrary shell
+	command that takes a single argument, namely the sha1 to update to.
 +
 If the submodule is not yet initialized, and you just want to use the
 setting as stored in .gitmodules, you can automatically initialize the

Documentation/gitmodules.txt

@@ -55,10 +55,6 @@ submodule.<name>.branch::
 	A remote branch name for tracking updates in the upstream submodule.
 	If the option is not specified, it defaults to 'master'.  See the
 	`--remote` documentation in linkgit:git-submodule[1] for details.
-+
-This branch name is also used for the local branch created by
-non-checkout cloning updates.  See the `update` documentation in
-linkgit:git-submodule[1] for details.
 
 submodule.<name>.fetchRecurseSubmodules::
 	This option can be used to control recursive fetching of this

git-submodule.sh

@@ -246,9 +246,6 @@ module_name()
 # $3 = URL to clone
 # $4 = reference repository to reuse (empty for independent)
 # $5 = depth argument for shallow clones (empty for deep)
-# $6 = (remote-tracking) starting point for the local branch (empty for HEAD)
-# $7 = local branch to create (empty for a detached HEAD, unless $6 is
-#      also empty, in which case the local branch is left unchanged)
 #
 # Prior to calling, cmd_update checks that a possibly existing
 # path is not a git repository.
@@ -262,8 +259,6 @@ module_clone()
 	url=$3
 	reference="$4"
 	depth="$5"
-	start_point="$6"
-	local_branch="$7"
 	quiet=
 	if test -n "$GIT_QUIET"
 	then
@@ -317,16 +312,7 @@ module_clone()
 	echo "gitdir: $rel/$a" >"$sm_path/.git"
 
 	rel=$(echo $a | sed -e 's|[^/][^/]*|..|g')
-	(
-		clear_local_git_env
-		cd "$sm_path" &&
-		GIT_WORK_TREE=. git config core.worktree "$rel/$b" &&
-		# ash fails to wordsplit ${local_branch:+-B "$local_branch"...}
-		case "$local_branch" in
-		'') git checkout -f -q ${start_point:+"$start_point"} ;;
-		?*) git checkout -f -q -B "$local_branch" ${start_point:+"$start_point"} ;;
-		esac
-	) || die "$(eval_gettext "Unable to setup cloned submodule '\$sm_path'")"
+	(clear_local_git_env; cd "$sm_path" && GIT_WORK_TREE=. git config core.worktree "$rel/$b")
 }
 
 isnumber()
@@ -489,15 +475,16 @@ Use -f if you really want to add it." >&2
 				echo "$(eval_gettext "Reactivating local git directory for submodule '\$sm_name'.")"
 			fi
 		fi
-		if test -n "$branch"
-		then
-			start_point="origin/$branch"
-			local_branch="$branch"
-		else
-			start_point=""
-			local_branch=""
-		fi
-		module_clone "$sm_path" "$sm_name" "$realrepo" "$reference" "$depth" "$start_point" "$local_branch" || exit
+		module_clone "$sm_path" "$sm_name" "$realrepo" "$reference" "$depth" || exit
+		(
+			clear_local_git_env
+			cd "$sm_path" &&
+			# ash fails to wordsplit ${branch:+-b "$branch"...}
+			case "$branch" in
+			'') git checkout -f -q ;;
+			?*) git checkout -f -q -B "$branch" "origin/$branch" ;;
+			esac
+		) || die "$(eval_gettext "Unable to checkout submodule '\$sm_path'")"
 	fi
 	git config submodule."$sm_name".url "$realrepo"
 
@@ -818,9 +805,7 @@ cmd_update()
 		fi
 		name=$(module_name "$sm_path") || exit
 		url=$(git config submodule."$name".url)
-		config_branch=$(get_submodule_config "$name" branch)
-		branch="${config_branch:-master}"
-		local_branch="$branch"
+		branch=$(get_submodule_config "$name" branch master)
 		if ! test -z "$update"
 		then
 			update_module=$update
@@ -834,19 +819,11 @@ cmd_update()
 
 		displaypath=$(relative_path "$prefix$sm_path")
 
-		case "$update_module" in
-		none)
+		if test "$update_module" = "none"
+		then
 			echo "Skipping submodule '$displaypath'"
 			continue
-			;;
-		checkout)
-			local_branch=""
-			;;
-		rebase | merge | !*)
-			;;
-		*)
-			die "$(eval_gettext "Invalid update mode '$update_module' for submodule '$name'")"
-		esac
+		fi
 
 		if test -z "$url"
 		then
@@ -860,8 +837,7 @@ Maybe you want to use 'update --init'?")"
 
 		if ! test -d "$sm_path"/.git -o -f "$sm_path"/.git
 		then
-			start_point="origin/${branch}"
-			module_clone "$sm_path" "$name" "$url" "$reference" "$depth" "$start_point" "$local_branch" || exit
+			module_clone "$sm_path" "$name" "$url" "$reference" "$depth" || exit
 			cloned_modules="$cloned_modules;$name"
 			subsha1=
 		else
@@ -907,7 +883,7 @@ Maybe you want to use 'update --init'?")"
 			case ";$cloned_modules;" in
 			*";$name;"*)
 				# then there is no local change to integrate
-				update_module='!git reset --hard -q'
+				update_module=checkout ;;
 			esac
 
 			must_die_on_failure=

t/t7406-submodule-update.sh

@@ -63,9 +63,6 @@ test_expect_success 'setup a submodule tree' '
 	 git submodule add ../none none &&
 	 test_tick &&
 	 git commit -m "none"
-	) &&
-	(cd super &&
-	 git tag initial-setup
 	)
 '
 
@@ -706,7 +703,7 @@ test_expect_success 'submodule update places git-dir in superprojects git-dir re
 	git clone super_update_r super_update_r2 &&
 	(cd super_update_r2 &&
 	 git submodule update --init --recursive >actual &&
-	 test_i18ngrep "Submodule path .submodule/subsubmodule.: .git reset --hard -q" actual &&
+	 test_i18ngrep "Submodule path .submodule/subsubmodule.: checked out" actual &&
 	 (cd submodule/subsubmodule &&
 	  git log > ../../expected
 	 ) &&
@@ -777,38 +774,4 @@ test_expect_success 'submodule update --recursive drops module name before recur
 	 test_i18ngrep "Submodule path .deeper/submodule/subsubmodule.: checked out" actual
 	)
 '
-
-test_expect_success 'submodule update --checkout clones detached HEAD' '
-	git clone super super4 &&
-	echo "detached HEAD" >expected &&
-	(cd super4 &&
-	 git reset --hard initial-setup &&
-	 git submodule init submodule &&
-	 git submodule update >> /tmp/log 2>&1 &&
-	 (cd submodule &&
-	  git symbolic-ref HEAD > ../../actual ||
-	  echo "detached HEAD" > ../../actual
-	 )
-	) &&
-	test_cmp actual expected &&
-	rm -rf super4
-'
-
-test_expect_success 'submodule update --merge clones attached HEAD' '
-	git clone super super4 &&
-	echo "refs/heads/master" >expected &&
-	(cd super4 &&
-	 git reset --hard initial-setup &&
-	 git submodule init submodule &&
-	 git config submodule.submodule.update merge &&
-	 git submodule update --merge &&
-	 (cd submodule &&
-	  git symbolic-ref HEAD > ../../actual ||
-	  echo "detached HEAD" > ../../actual
-	 )
-	) &&
-	test_cmp actual expected &&
-	rm -rf super4
-'
-
 test_done