tests: add test of resolution of content-divergent stacks
This patch adds a test of resolution of content-divergence stacks where a series
of changesets get mutated as two different series resulting in whole
content-divergent stacks.
As the tests shows, we are not processing the changesets in right order which
needs to be fixed first.
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
^tests/.*\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes
^docs/training/graphs/
^docs/training/html/
^docs/training/index.html
^docs/training/graphviz-images/
^docs/training/img/
^docs/training/output/
^docs/training/pandocfilters/