[PATCH] Teach git-submodule to use master's remote when updating subprojects

[Mark Levedahl <mlevedahl@gmail.com>]

Modules that are defined using relative urls to the master project are
assumed to be completely owned by the project. When running
"submodule update" from the top level, it is reasonable that the entire
project exists at the current master's remote. Using the
branch.$name.remote machinery, this remote can be different for each
branch and can be different than the current defaults in each submodule.

This teaches submodule to:

1) Possibly define the current master's remote in each submodule, using
the same relative url used by submodule init.
2) Fetch each submodule's updates from the master's remote.

Submodules defined using absolute urls (not relative to the parent) are
not touched by this logic. These modules are assumed to be independent
of the master project so submodule can do no better than to fetch from
their currently defined default remotes as already done.


Signed-off-by: Mark Levedahl <mlevedahl@gmail.com>
---
 git-submodule.sh |   20 +++++++++++++++++++-
 1 files changed, 19 insertions(+), 1 deletions(-)

diff --git a/git-submodule.sh b/git-submodule.sh
index 42be4b9..5b4b16f 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -209,11 +209,14 @@ modules_init()
 
 #
 # Update each submodule path to correct revision, using clone and checkout as needed
+# For owned submodules (defined using relative url), we use master project's remote
+# and define that in each submodule if not already there
 #
 # $@ = requested paths (default to all)
 #
 modules_update()
 {
+	master_remote=$(get_default_remote)
 	git ls-files --stage -- "$@" | grep -e '^160000 ' |
 	while read mode sha1 stage path
 	do
@@ -240,9 +243,24 @@ modules_update()
 			die "Unable to find current revision in submodule path '$path'"
 		fi
 
+		baseurl="$(GIT_CONFIG=.gitmodules git config submodule."$name".url)"
+		case "$baseurl" in
+		./*|../*)
+			fetch_remote=$master_remote
+			(unset GIT_DIR ; cd "$path" && git config remote."$fetch_remote".url > nul) ||
+			(
+				absurl="$(resolve_relative_url $baseurl)"
+				unset GIT_DIR; cd "$path" && git remote add "$master_remote" "$absurl"
+			) || die "Unable to define remote '$fetch_remote' in submodule path '$path'"
+			;;
+		*)
+			fetch_remote=
+			;;
+		esac
+
 		if test "$subsha1" != "$sha1"
 		then
-			(unset GIT_DIR; cd "$path" && git-fetch &&
+			(unset GIT_DIR; cd "$path" && git-fetch "$fetch_remote" &&
 				git-checkout -q "$sha1") ||
 			die "Unable to checkout '$sha1' in submodule path '$path'"
 
-- 
1.5.4.rc3.14.gc50f