Merge branch 'al/mergetool-printf-fix' into maint

* al/mergetool-printf-fix:
  difftool--helper: fix printf usage
  git-mergetool: print filename when it contains %

Author: gitster

git-difftool--helper.sh

@@ -40,7 +40,7 @@ launch_merge_tool () {
 	# the user with the real $MERGED name before launching $merge_tool.
 	if should_prompt
 	then
-		printf "\nViewing: '$MERGED'\n"
+		printf "\nViewing: '%s'\n" "$MERGED"
 		if use_ext_cmd
 		then
 			printf "Launch '%s' [Y/n]: " \

git-mergetool.sh

@@ -440,7 +440,7 @@ then
 fi
 
 printf "Merging:\n"
-printf "$files\n"
+printf "%s\n" "$files"
 
 IFS='
 '