[PATCH 2/4] submodule: fix recursive execution from non root directory

[Stefan Beller <sbeller@google.com>]

One of the first things that happens in most submodule sub commands is

    git submodule--helper list --prefix "$wt_prefix"

Currently the passed --prefix is used for doing path calculation
as if we were in that path relative to the repository root, which is
why we need to pass "$wt_prefix". The more common way in Git however
would be to use

    git -C "$wt_prefix" submodule--helper list

which I want to change later. That way however does not just
pass the prefix into the submodule command, but also changes
into that directory.

Say you have the following setup

repo/ # a superproject repository
repo/untracked/ # an untracked dir in repo/
repo/sub/ # a submodule
repo/sub/subsub # a submodule of a submodule

When in repo/untracked/ and invoking "git submodule status --recursive",
the recursed instance of the latter version for listing submodules would
try to change into the directory repo/sub/untracked, which is a bug.
This happens as we cd into the submodule in git-submodule.sh without
clearing wt_prefix, which is the assumed relative path inside the working
directory.

Most times that directory doesn't exist and we error out. Fix this bug
by clearing wt_prefix, such that any recursive instances of will assume
to operate from the respective root of the respective submodule.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 git-submodule.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/git-submodule.sh b/git-submodule.sh
index 536ba68..6b18a03 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -827,6 +827,7 @@ Maybe you want to use 'update --init'?")"
 			(
 				prefix="$(relative_path $prefix$sm_path)/"
 				clear_local_git_env
+				wt_prefix=
 				cd "$sm_path" &&
 				eval cmd_update
 			)
@@ -1159,6 +1160,7 @@ cmd_status()
 			(
 				prefix="$displaypath/"
 				clear_local_git_env
+				wt_prefix=
 				cd "$sm_path" &&
 				eval cmd_status
 			) ||
@@ -1240,6 +1242,7 @@ cmd_sync()
 
 				if test -n "$recursive"
 				then
+					wt_prefix=
 					eval cmd_sync
 				fi
 			)
-- 
2.8.0.rc4.10.g52f3f33