debian: don't delete evolve and topic extensions
The debian packaging rules deletes all __init__.py to avoid
conflicting with the __init__.py that declares the namespace
package. Now that the evolve and topic extensions also live in
__init__.py files, we clearly don't want to delete all __init__.py
files anymore; only the hgext3rd/__init__.py should be deleted.
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)