Avoid race condition when listing matches (#238)

z.sh

@@ -147,15 +147,15 @@ _z() {
             function output(matches, best_match, common) {
                 # list or return the desired directory
                 if( list ) {
+                    if( common ) {
+                        printf "%-10s %s\n", "common:", common > "/dev/stderr"
+                    }
                     cmd = "sort -n >&2"
                     for( x in matches ) {
                         if( matches[x] ) {
                             printf "%-10s %s\n", matches[x], x | cmd
                         }
                     }
-                    if( common ) {
-                        printf "%-10s %s\n", "common:", common > "/dev/stderr"
-                    }
                 } else {
                     if( common ) best_match = common
                     print best_match