Convert to use quiet option when available

A minor fix that eliminates usage of "2>/dev/null" when --quiet or
-q has already been implemented.

Signed-off-by: Dan Loewenherz <daniel.loewenherz@yale.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-filter-branch.sh

@@ -430,7 +430,7 @@ if [ "$filter_tag_name" ]; then
 		if [ "$type" = "tag" ]; then
 			# Dereference to a commit
 			sha1t="$sha1"
-			sha1="$(git rev-parse "$sha1"^{commit} 2>/dev/null)" || continue
+			sha1="$(git rev-parse -q "$sha1"^{commit})" || continue
 		fi
 
 		[ -f "../map/$sha1" ] || continue

git-merge-resolve.sh

@@ -37,7 +37,7 @@ then
 	exit 2
 fi
 
-git update-index --refresh 2>/dev/null
+git update-index -q --refresh
 git read-tree -u -m --aggressive $bases $head $remotes || exit 2
 echo "Trying simple merge."
 if result_tree=$(git write-tree 2>/dev/null)

git-parse-remote.sh

@@ -2,7 +2,7 @@
 
 # git-ls-remote could be called from outside a git managed repository;
 # this would fail in that case and would issue an error message.
-GIT_DIR=$(git rev-parse --git-dir 2>/dev/null) || :;
+GIT_DIR=$(git rev-parse -q --git-dir) || :;
 
 get_data_source () {
 	case "$1" in

git-pull.sh

@@ -147,7 +147,7 @@ then
 	echo >&2 "Warning: fetch updated the current branch head."
 	echo >&2 "Warning: fast forwarding your working tree from"
 	echo >&2 "Warning: commit $orig_head."
-	git update-index --refresh 2>/dev/null
+	git update-index -q --refresh
 	git read-tree -u -m "$orig_head" "$curr_head" ||
 		die 'Cannot fast-forward your working tree.
 After making sure that you saved anything precious from