Shell utilities: Guard against expr' magic tokens.

Some words, e.g., `match', are special to expr(1), and cause strange
parsing effects.  Track down all uses of expr and mangle the arguments
so that this isn't a problem.

Signed-off-by: Mark Wooding <mdw@distorted.org.uk>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-merge-one-file.sh

@@ -26,7 +26,7 @@ case "${1:-.}${2:-.}${3:-.}" in
 	fi
 	if test -f "$4"; then
 		rm -f -- "$4" &&
-		rmdir -p "$(expr "$4" : '\(.*\)/')" 2>/dev/null || :
+		rmdir -p "$(expr "z$4" : 'z\(.*\)/')" 2>/dev/null || :
 	fi &&
 		exec git-update-index --remove -- "$4"
 	;;