In order to have as few problems as possible for people who install bk, our install package includes a number of tools for people who install bk. One of those in GNU diff in src/gnu/difftutils
This copy of diff is rather old (v2.7) and will cause people trying to package bk headaches. In does have some custom modifications to add special support for ignoring differences on line-ending conditions.
However, bk no longer uses GNU diff internally because we implemented our own diff algorithm to have more control and better alignment in the weave. We do still have a
_BK_USE_EXTERNAL_DIFF override int the environment that we use for testing.
We should just remove that diff.