From bb662808db2be22b349dc0aa0b4d4be934df666b Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Fri, 18 Oct 2019 18:31:50 -0400
Subject: [PATCH] GNUmakefile: fix blank line handling in SageMath listings.

---
 GNUmakefile                   | 5 +++--
 sage_listings/example.listing | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/GNUmakefile b/GNUmakefile
index 19bde1d..e9b7d11 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -175,9 +175,10 @@ $(PN).log: $(SRCS)
 	$(MAKE)
 
 # How do we convert a raw listing into something testable by sage? We
-# append/prepend triple quotes to make the whole thing into a doctest.
+# append/prepend triple quotes to make the whole thing into a doctest,
+# and then we replace any blank lines by "<BLANKLINE>".
 sage_listings/%.py: sage_listings/%.listing
-	echo '"""' > $@ && cat $< >> $@ && echo '"""' >> $@
+	echo '"""' > $@ && cat $< >> $@ && echo '"""' >> $@ && sed -i 's/^[[:space:]]*$$/<BLANKLINE>/' $@
 
 # Ensure that there are no overfull or underfull boxes in the output
 # document by parsing the log for said warnings.
diff --git a/sage_listings/example.listing b/sage_listings/example.listing
index d475764..c59a662 100644
--- a/sage_listings/example.listing
+++ b/sage_listings/example.listing
@@ -1,2 +1,4 @@
 sage: Cone([(1,0),(0,1)]).lyapunov_rank()
 2
+sage: print("")
+
-- 
2.43.2