Fixed /cgi/schema validation for EPrints XML

Manually applied from master:
01c78f5f78c1e1b8a41c42bd1b47e26a0eae0c6e
cc1dc564c8e02f28ddecc4dcc0e379f02ee4376e
86ec7bc6d267c2aec71b2014d4ebedf7f6ad302c

(Still learning how to do things properly in git)