Fix bogus bash binary location

lib/history.bash

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # append to bash_history if Terminal.app quits
 shopt -s histappend
@@ -17,4 +17,4 @@ export AUTOFEATURE=true autotest
 
 function rh {
   history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
-}
+}