Cannot rename pages due to MethodInvocationException on hasChildren

When attempting to rename a page by editing at http://extranet.atlassian.com/pages/editpage.action?pageId=620691550 then typing in a new name and clicking save, the attached error page is thrown.

Cause:
org.apache.velocity.exception.MethodInvocationException: Invocation of method 'hasChildren' in class com.atlassian.confluence.pages.Page threw exception class net.sf.hibernate.LazyInitializationException : Failed to lazily initialize a collection
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:309)
caused by: net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection
at net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:201)
caused by: net.sf.hibernate.HibernateException: collection was evicted
at net.sf.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:3305)

Stack Trace: [hide]

org.apache.velocity.exception.MethodInvocationException: Invocation of method 'hasChildren' in class com.atlassian.confluence.pages.Page threw exception class net.sf.hibernate.LazyInitializationException : Failed to lazily initialize a collection
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:309)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:207)
at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:357)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:135)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:232)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:153)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:94)
at com.atlassian.confluence.setup.velocity.ApplyDecoratorDirective.render(ApplyDecoratorDirective.java:159)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:153)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271)
at org.apache.velocity.Template.merge(Template.java:296)
at com.opensymphony.webwork.dispatcher.VelocityResult.doExecute(VelocityResult.java:91)
at com.atlassian.xwork.results.ProfiledVelocityResult.doExecute(ProfiledVelocityResult.java:21)
at com.opensymphony.webwork.dispatcher.WebWorkResultSupport.execute(WebWorkResultSupport.java:116)
...