submodule: add --dissociate option to add/update commands

Add --dissociate option to add and update commands, both clone helper commands
that already have the --reference option --dissociate pairs with.

Signed-off-by: Casey Fitzpatrick <kcghost@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-submodule.sh

@@ -42,6 +42,7 @@ prefix=
 custom_name=
 depth=
 progress=
+dissociate=
 
 die_if_unmatched ()
 {
@@ -128,6 +129,9 @@ cmd_add()
 		--reference=*)
 			reference_path="${1#--reference=}"
 			;;
+		--dissociate)
+			dissociate=1
+			;;
 		--name)
 			case "$2" in '') usage ;; esac
 			custom_name=$2
@@ -258,7 +262,7 @@ or you are unsure what this means choose another name with the '--name' option."
 				eval_gettextln "Reactivating local git directory for submodule '\$sm_name'."
 			fi
 		fi
-		git submodule--helper clone ${GIT_QUIET:+--quiet} ${progress:+"--progress"} --prefix "$wt_prefix" --path "$sm_path" --name "$sm_name" --url "$realrepo" ${reference:+"$reference"} ${depth:+"$depth"} || exit
+		git submodule--helper clone ${GIT_QUIET:+--quiet} ${progress:+"--progress"} --prefix "$wt_prefix" --path "$sm_path" --name "$sm_name" --url "$realrepo" ${reference:+"$reference"} ${dissociate:+"--dissociate"} ${depth:+"$depth"} || exit
 		(
 			sanitize_submodule_env
 			cd "$sm_path" &&
@@ -493,6 +497,9 @@ cmd_update()
 		--reference=*)
 			reference="$1"
 			;;
+		--dissociate)
+			dissociate=1
+			;;
 		-m|--merge)
 			update="merge"
 			;;
@@ -550,6 +557,7 @@ cmd_update()
 		${prefix:+--recursive-prefix "$prefix"} \
 		${update:+--update "$update"} \
 		${reference:+"$reference"} \
+		${dissociate:+"--dissociate"} \
 		${depth:+--depth "$depth"} \
 		$recommend_shallow \
 		$jobs \