[PATCH] pre-commit.sample: don't print incidental SHA1

Make the sample pre-commit hook script discard
all git-rev-parse output, not just stderr.
Otherwise, it would print an SHA1.

Signed-off-by: Jim Meyering <redacted>
---
[this patch applies at least to "next"]
I enabled the sample pre-commit hook and was surprised to
see new output with every commit.  It was due to that script's
use of git-rev-parse.

Also, I noticed the use of "git-hyphen" git-rev-parse.
Perhaps that hyphen has been left in deliberately,
for portability to very old versions of git?

While the 800+ uses of "git rev-parse" far outnumber uses of the
two-hyphen version, this is far from being the only use in code
(this is on the "next" branch):

  $ git grep -l git-rev-parse|grep -vE 'Docu|command-list|\.giti'
  contrib/emacs/git.el
  contrib/examples/git-revert.sh
  git-archimport.perl
  git-cvsexportcommit.perl
  git-cvsimport.perl
  git-submodule.sh
  gitweb/gitweb.perl
  perl/Git.pm
  templates/hooks--pre-commit.sample


 templates/hooks--pre-commit.sample |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/templates/hooks--pre-commit.sample b/templates/hooks--pre-commit.sample
index 0e49279..0ba6207 100755
--- a/templates/hooks--pre-commit.sample
+++ b/templates/hooks--pre-commit.sample

@@ -7,7 +7,7 @@
 #
 # To enable this hook, rename this file to "pre-commit".

-if git-rev-parse --verify HEAD 2>/dev/null
+if git-rev-parse --verify HEAD >/dev/null 2>&1
 then
 	against=HEAD
 else

-- 
1.6.3.1.83.g37eb7