Thanks to lots of work by Myron Wu, the version of
gitit in the GitHub repository now compiles with
pandoc 2.2.x. (Earlier versions aren't supported.)
If you've previously had trouble installing gitit,
you might try fetching and building the current code.
If you have the Haskell 'stack' tool installed, this should
work:
git clone
https://github.com/jgm/gitit.git
cd gitit
stack install