Sync with 2.4.10

git-submodule.sh

@@ -22,6 +22,15 @@ require_work_tree
 wt_prefix=$(git rev-parse --show-prefix)
 cd_to_toplevel
 
+# Restrict ourselves to a vanilla subset of protocols; the URLs
+# we get are under control of a remote repository, and we do not
+# want them kicking off arbitrary git-remote-* programs.
+#
+# If the user has already specified a set of allowed protocols,
+# we assume they know what they're doing and use that instead.
+: ${GIT_ALLOW_PROTOCOL=file:git:http:https:ssh}
+export GIT_ALLOW_PROTOCOL
+
 command=
 branch=
 force=