Fix for issue #6188

added code to master.py to check for users if they do't show up in pwd.getpwall. This can happen on LDAP-enabled user systems. You can see the
user not show up, but still be visible if you query for them directly.

Issue #6188 shows a problem when users ar ein LDAP but don't show up in pwd.getpwall. This change still allows the master.py process to create the key and accept the user if a direct lookup yields a result.