Catch some potential NPEs

James Moger

2015-11-18 def01db5f7dc1c607026528eed1dfd75c6e59779

 src/main/java/com/gitblit/manager/IUserManager.java

@@ -24,6 +24,7 @@
    *
    * @param username
    * @return true if the specified username represents an internal account
     * @since 1.4.0
    */
   boolean isInternalAccount(String username);