git-mergetool: check return value from read

Mostly fixed already by 6b44577 (mergetool: check return value
from read, 2011-07-01). Catch two uses it missed.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-mergetool--lib.sh

@@ -38,7 +38,7 @@ check_unchanged () {
 		while true; do
 			echo "$MERGED seems unchanged."
 			printf "Was the merge successful? [y/n] "
-			read answer
+			read answer || return 1
 			case "$answer" in
 			y*|Y*) status=0; break ;;
 			n*|N*) status=1; break ;;

git-mergetool.sh

@@ -72,7 +72,7 @@ describe_file () {
 resolve_symlink_merge () {
     while true; do
 	printf "Use (l)ocal or (r)emote, or (a)bort? "
-	read ans
+	read ans || return 1
 	case "$ans" in
 	    [lL]*)
 		git checkout-index -f --stage=2 -- "$MERGED"