Add a comment about SOURCE_DATE_EPOCH to the makefile.

diff --git a/makefile b/makefile
index 1486a26fbff7d5d1b46f01dcf19f8f744c0987c1..6cd7eee13b7153b014dd4076b7463f6fa11fc4e8 100644 (file)
--- a/makefile
+++ b/makefile
@@ -41,6 +41,14 @@ SRCS = $(PN).tex $(shell kpsewhich $(BIBS)) $(shell kpsewhich $(MJOTEX))
 # The process is kind of like finding a fixpoint of `make` with
 # respect to the contents of the aux file.
 #
+# Why use the aux file and not the PDF, which is what we really care
+# about? The pdflatex tool currently embeds the creation/modification
+# time into the PDF, so every new version will differ from the last,
+# making comparisons meaningless. This is fixed in pdftex v1.40.17
+# thanks to Debian's SOURCE_DATE_EPOCH initiative. When that version
+# of pdflatex makes it into TeX Live 2016, we can replace this junk
+# with something smarter
+#
 $(PN).pdf: $(SRCS) $(PN).aux $(PN).bbl
        mv $(PN).aux $(PN).aux.bak
        $(LATEX) $< && $(LATEX) $<