topic: check that repo.currenttopic is set before using it as an argument
repo.currenttopic can be an empty string, which means there's no current topic
set. This fact can be used to short-circuit some checks.
Also, this avoids passing an empty string as an argument to topic() revset.
exclude contrib
recursive-exclude contrib *
exclude hgext3rd/evolve/hack
recursive-exclude hgext3rd/evolve/hack *
exclude hgext3rd/evolve/legacy.py
exclude Makefile
exclude tests/test-drop.t
exclude tests/test-inhibit.t
exclude tests/test-oldconvert.t
exclude docs/tutorial/.netlify
include COPYING
include docs/figures/hgview-example.png
include docs/makefile
include docs/*.py
include docs/README
include docs/*.rst
include docs/static/*.svg
include docs/tutorials/*.t
include hgext3rd/__init__.py
include hgext3rd/evolve/*.py
include hgext3rd/evolve/thirdparty/*.py
include hgext3rd/topic/*.py
include hgext3rd/topic/README
include MANIFEST.in
include README
include CHANGELOG
include setup.py
include tests/*.py
include tests/*.sh
include tests/testlib/*.sh
include tests/*.t
recursive-include docs/tutorial *.rst
recursive-include docs/tutorial *.css
include docs/tutorial/standalone.html
recursive-include docs/tutorial *.js
recursive-include docs/tutorial *.md
recursive-include docs/tutorial *.py
recursive-include docs/tutorial *.sh
recursive-include docs/tutorial *.t
prune debian
recursive-include docs/figures *.svg