Correct usages of sed in git-tag for Mac OS X

Both `git-tag -l` and `git tag -v` fail on Mac OS X due to their
non-standard uses of sed.  Actually `git tag -v` fails because the
underlying git-tag-verify uses a non-standard sed command.

We now stick to only standard sed, which does make our sed scripts
slightly more complicated, but we can actually list tags with more
than 0 lines of additional context and we can verify signed tags
with gpg.  These major Git functions are much more important than
saving two or three lines of a simple sed script.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-tag.sh

@@ -51,12 +51,16 @@ do
 		[ "$LINES" -le 0 ] && { echo "$TAG"; continue ;}
 		OBJTYPE=$(git cat-file -t "$TAG")
 		case $OBJTYPE in
-		tag)	ANNOTATION=$(git cat-file tag "$TAG" |
-				       sed -e '1,/^$/d' \
-					   -e '/^-----BEGIN PGP SIGNATURE-----$/Q' )
-			printf "%-15s %s\n" "$TAG" "$ANNOTATION" |
-			  sed -e '2,$s/^/    /' \
-			      -e "${LINES}q"
+		tag)
+			ANNOTATION=$(git cat-file tag "$TAG" |
+				sed -e '1,/^$/d' |
+				sed -n -e "
+					/^-----BEGIN PGP SIGNATURE-----\$/q
+					2,\$s/^/    /
+					p
+					${LINES}q
+				")
+			printf "%-15s %s\n" "$TAG" "$ANNOTATION"
 			;;
 		*)      echo "$TAG"
 			;;

git-verify-tag.sh

@@ -37,8 +37,9 @@ esac
 trap 'rm -f "$GIT_DIR/.tmp-vtag"' 0
 
 git-cat-file tag "$1" >"$GIT_DIR/.tmp-vtag" || exit 1
-
-cat "$GIT_DIR/.tmp-vtag" |
-sed '/-----BEGIN PGP/Q' |
+sed -n -e '
+	/^-----BEGIN PGP SIGNATURE-----$/q
+	p
+' <"$GIT_DIR/.tmp-vtag" |
 gpg --verify "$GIT_DIR/.tmp-vtag" - || exit 1
 rm -f "$GIT_DIR/.tmp-vtag"