Silence git-hooks/pre-commit in the absence of .gitmodules.

git-hooks/pre-commit

Index: git-hooks/pre-commit
===================================================================
--- git-hooks/pre-commit	(revision 249215)
+++ git-hooks/pre-commit	(working copy)
@@ -23,7 +23,8 @@
   exit 1
 fi
 
-if test "$(git diff-index --cached HEAD .gitmodules)"; then
+if [[ -n "$(git ls-files .gitmodules)" &&

[Ami GONE FROM CHROMIUM, 2014/03/10 19:04:49]

Sample noise that this silences:
fatal: ambiguous argument '.gitmodules': unknown revision or path not in the
working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

FWIW I replaced "test" with "[[" b/c [[ short-circuits evaluation while test
does not (so keeping "test" would require a nested:
if test -n "$(..ls-files..)"; then
  if test -n "$(..diff-index..)"; then
The [[ form seems clearer to me but I don't really care.

+      -n "$(git diff-index --cached HEAD .gitmodules)" ]]; then
   cat <<EOF 1>&2
 You are trying to commit a change to .gitmodules.  That is not allowed.
 To make changes to submodule names/paths, edit DEPS.