Moving back and forth between revisions seems like a basic thing that one would want to do frequently.

If one has no uncommitted changes in the working directory one can just use hg update but if one has uncommitted changes then one can shelve them and unshelve them when one gets back using the hgshelve extension.

This seems like an essential basic requirement yet shelve is an extension and not part of the core of mercurial that is delivered when you install mercurial. Am I missing something? Is there some other way that this is usually done?

Thanks.