Consider using Mercurial patch queues to manage local changes. With MQ you can queue up local changes and stash them out of the way for future use.
For the extension's documentation, here's the standard workflow you'd use for putting away local changes for future use:
$ hg qnew choosename
$ hg qpop
$ # ...
$ # restore
$ hg qpush
$ hg strip -k choosename
$ hg qremove choosename
There's also shelve, but I've never used it.