stack: use stack._revs instead of stack.revs[1:] in external children revset
The revset in question excludes all revs that are part of the stack. Using
stack.revs[1:] works (rev #0 is stack base, which is not a part of the stack),
but using stack._revs is technically more correct, because this variable is
specifically designed to hold only revisions that are part of the stack.
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)