copyright: repair SOURCE_DATE_EPOCH from nix

- fixes: haskellfoundation#58 ...again

Author: doyougnu

Makefile

@@ -7,7 +7,7 @@ SPHINXOPTS    ?=
 SPHINXBUILD   ?= sphinx-build
 SOURCEDIR     = .
 BUILDDIR      = _build
-# SOURCE_DATE_EPOCH = $(shell git log -1 --format=%ct)
+SOURCE_DATE_EPOCH = $(shell git log -1 --format=%ct)
 
 # Put it first so that "make" without argument is like "make help".
 help:

hoh.nix

@@ -31,6 +31,10 @@ pkgs.stdenv.mkDerivation {
    src     = ./.;
    propagatedBuildInputs = pythonInputs ++ nonPythonInputs;
 
+   preBuild = ''
+  SOURCE_DATE_EPOCH="$(${pkgs.coreutils}/bin/date '+%s')"
+  '';
+
    buildPhase = ''
    runHook preBuild
    make ${target} SPHINXOPTS="-W"

src/Measurement_Observation/Measurement_Libs/weigh.rst

@@ -10,7 +10,7 @@ useful to confirm that a data structure or function has the memory performance
 you anticipate it to have at *runtime*. ``Weigh`` is easy to setup and
 non-invasive; requiring no changes to source code. Thus, it is a good *initial*
 tool to use before trying more advanced methods with higher setup costs, such as
-:ref:`Cachegrind <Cachegrind>`.
+:ref:`Cachegrind <Cachegrind Chapter>`.
 
 
 Requirements