keyword: (bugfix) only set changenode for kwtemplater when committing
kwexpand must always obtain changenode from filectx,
otherwise current changenode is expanded in every file.
Also fixes "hg cat <more than 1 file>".
To run the tests, do:
cd tests/
python run-tests.py
See http://www.selenic.com/mercurial/wiki/index.cgi/WritingTests for
more information on writing tests.