tests: show how `hg split` can put color codes in commit template

Authored by martinvonz.


tests: show how hg split can put color codes in commit template

With D9255, I made it so hg split respects the
commmand-templates.oneline-summary config. I don't think I realized
that the output I modified was being put in a commit message
template. The result was that if you have coloring enabled, you get
colors in the commit template. This patch show that. The test is
unfortunately pretty verbose (like most other hg split tests) and
shows a bunch of irrelevant "color codes" (templater labels).

Differential Revision: https://phab.mercurial-scm.org/D9321