[PATCH] Optimize usage of grep by passing -q

[Stefan Beller <sbeller@google.com>]

Instead of redirecting all grep output to /dev/null, we can just
pass in -q instead. This preserves the exit code behavior, but is faster.
As grep returns true if it finds at least one match, grep can exit promptly
after finding the first line and doesn't need to find more occurrences
which would be redirected to /dev/null anyways.

This is true for the gnu version of grep. I am not sure if all
versions of grep support this optimization. In case it is not,
we'd revert this patch.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 git-bisect.sh              | 5 ++---
 git-rebase--interactive.sh | 2 +-
 git-rebase.sh              | 2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/git-bisect.sh b/git-bisect.sh
index 5d1cb00..b909605 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -519,8 +519,7 @@ exit code \$res from '\$command' is < 0 or >= 128" >&2
 
 		cat "$GIT_DIR/BISECT_RUN"
 
-		if sane_grep "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN" \
-			>/dev/null
+		if sane_grep -q "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN"
 		then
 			gettextln "bisect run cannot continue any more" >&2
 			exit $res
@@ -533,7 +532,7 @@ exit code \$res from '\$command' is < 0 or >= 128" >&2
 			exit $res
 		fi
 
-		if sane_grep "is the first $TERM_BAD commit" "$GIT_DIR/BISECT_RUN" >/dev/null
+		if sane_grep -q "is the first $TERM_BAD commit" "$GIT_DIR/BISECT_RUN"
 		then
 			gettextln "bisect run success"
 			exit 0;
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index d65c06e..f360ac0 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -1225,7 +1225,7 @@ then
 	git rev-list $revisions |
 	while read rev
 	do
-		if test -f "$rewritten"/$rev && test "$(sane_grep "$rev" "$state_dir"/not-cherry-picks)" = ""
+		if test -f "$rewritten"/$rev && test "$(sane_grep -q "$rev" "$state_dir"/not-cherry-picks)"
 		then
 			# Use -f2 because if rev-list is telling us this commit is
 			# not worthwhile, we don't want to track its multiple heads,
diff --git a/git-rebase.sh b/git-rebase.sh
index af7ba5f..b6a5f73 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -578,7 +578,7 @@ mb=$(git merge-base "$onto" "$orig_head")
 if test "$type" != interactive && test "$upstream" = "$onto" &&
 	test "$mb" = "$onto" && test -z "$restrict_revision" &&
 	# linear history?
-	! (git rev-list --parents "$onto".."$orig_head" | sane_grep " .* ") > /dev/null
+	! (git rev-list --parents "$onto".."$orig_head" | sane_grep -q " .* ")
 then
 	if test -z "$force_rebase"
 	then
-- 
2.6.3.368.gf34be46