tests/test-template-engine.t

import: wrap a transaction around the whole command

Now 'rollback' after 'import' is less surprising: it rolls back all of
the imported changesets, not just the last one. As an extra added
benefit, you don't need 'rollback -f' after 'import --bypass', which
was an undesired side effect of fixing issue2998 (59e8bc22506e)..

Note that this is a different take on issue963, which complained that
rollback after importing multiple patches returned the working dir
parent to the starting point, not to the second-last patch applied.
Since we now rollback the entire import, returning the working dir to
the starting point is entirely logical. So this change also undoes
a732eebf1958, the fix to issue963, and updates its tests accordingly.

Bottom line: rollback after import was weird before issue963,
understandable since the fix for issue963, and even better now.

  $ cat > engine.py << EOF
  > 
  > from mercurial import templater
  > 
  > class mytemplater(object):
  >     def __init__(self, loader, filters, defaults):
  >         self.loader = loader
  > 
  >     def process(self, t, map):
  >         tmpl = self.loader(t)
  >         for k, v in map.iteritems():
  >             if k in ('templ', 'ctx', 'repo', 'revcache', 'cache'):
  >                 continue
  >             if hasattr(v, '__call__'):
  >                 v = v(**map)
  >             v = templater.stringify(v)
  >             tmpl = tmpl.replace('{{%s}}' % k, v)
  >         yield tmpl
  > 
  > templater.engines['my'] = mytemplater
  > EOF
  $ hg init test
  $ echo '[extensions]' > test/.hg/hgrc
  $ echo "engine = `pwd`/engine.py" >> test/.hg/hgrc
  $ cd test
  $ cat > mymap << EOF
  > changeset = my:changeset.txt
  > EOF
  $ cat > changeset.txt << EOF
  > {{rev}} {{node}} {{author}}
  > EOF
  $ hg ci -Ama
  adding changeset.txt
  adding mymap
  $ hg log --style=./mymap
  0 97e5f848f0936960273bbf75be6388cd0350a32b test