Do not build the "longhtml" version for pre-release versions.
diff --git a/Doc/Makefile b/Doc/Makefile
index db88c2c..c2ceb7c 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -310,7 +310,11 @@
zippdf: pdf-$(PAPER)-$(RELEASE).zip
ziplatex: latex-$(RELEASE).zip
-zips: zippdf zipps ziphtml ziplonghtml
+# Only build the longhtml version for final releases; use the second
+# version of this for pre-release versions.
+#
+#zips: zippdf zipps ziphtml ziplonghtml
+zips: zippdf zipps ziphtml
bziphtml: html-$(RELEASE).tar.bz2
bzipinfo: info-$(RELEASE).tar.bz2