The comment at the top of git-and-tools/default.nix said:
/* All git-relates tools live here, in a separate attribute set so that users
* can get a fast overview over what's available.
but unfortunately that hasn't actually held up in practice.
Git-related packages have continued to be added to the top level, or
into gitAndTools, or sometimes both, basically at random, so having
gitAndTools is just confusing. In fact, until I looked as part of
working on getting rid of gitAndTools, one program (ydiff) was
packaged twice independently, once in gitAndTools and once at the top
level (I fixed this in 98c3490196).
So I think it's for the best if we move away from gitAndTools, and
just put all the packages it previously contained at the top level.
I've implemented this here by just making gitAndTools an alias for the
top level -- this saves having loads of lines in aliases.nix. This
means that people can keep referring to gitAndTools in their
configuration, but it won't be allowed to be used within Nixpkgs, and
it won't be presented to new users by e.g. nix search.
The only other change here that I'm aware of is that
appendToName "minimal" is not longer called on the default git
package, because doing that would have necessitated having a private
gitBase variable like before. I think it makes more sense not to do
that anyway, and reserve the "minimal" suffix only for gitMinimal.
We were packaging ydiff twice!
In this patch, I've merged the two expressions into one, trying to
take the best of each. ydiff (top-level) didn't support being used as
a Python library, which is required by one other package (patroni), so
I chose gitAndTools.ydiff as the starting point, then moved in the
longDescription from the top-level one, as well as the code used to
run the tests.
While I was there, I fixed the tests, which were intended to be run by
the top-level ydiff but actually were not, because unlike mkDerivation
buildPythonApplication will not run `make test' by default.
Also, top-level ydiff previously propagated less and patchutils,
meaning they'd have been installed globally instead of just referenced
by ydiff. gitAndTools.ydiff just did nothing. Both also expected to
find git, hg, and svn in the environment, which was impure. So now
all these programs are referenced by store path from ydiff, for
purity.