evolve: extract the code computing dependencies in a separate function The code to compute dependencies between unstable changeset can be reused to compute the next reveset. This patch extracts it in its own function to make it reusable.

syntax: re
/figures/[^/]+\.png$
^docs/build/
^docs/html/
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$