tests: fix wordwrap tests

We now special-case each tag.  Use a special-cased tag.

Signed-off-by: David Aguilar <davvid@gmail.com>
doc: update v2.0.4 release notes draft

Signed-off-by: David Aguilar <davvid@gmail.com>
prefs: honor settings defined in /etc/gitconfig

Allow falling back to the values defined in /etc/gitconfig when asking
for "global" non-repo settings.

This fixes the ability to define user.email, user.name, cola.tabwidth,
and similar settings in /etc/gitconfig.

Closes #259

Reported-by: Leho Kraav <leho@kraav.com>
Signed-off-by: David Aguilar <davvid@gmail.com>