[PATCH] Documentation/Makefile: fix interrupted builds of user-manual.xml

[Jonathan Nieder <jrnieder@gmail.com>]

Unlike gcc, asciidoc does not atomically write its output file or
delete it when interrupted.  If it is interrupted in the middle of
writing an XML file, the result will be truncated input for xsltproc.

	XSLTPROC user-manual.html
	user-manual.xml:998: parser error : Premature end of data in t

Take care of this case by writing to a temporary and renaming it when
finished.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Based on a true story.

 Documentation/Makefile |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 8a8a395..04f69cf 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -264,7 +264,9 @@ manpage-base-url.xsl: manpage-base-url.xsl.in
 	mv $@+ $@
 
 user-manual.xml: user-manual.txt user-manual.conf
-	$(QUIET_ASCIIDOC)$(ASCIIDOC) $(ASCIIDOC_EXTRA) -b docbook -d book $<
+	$(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
+	$(ASCIIDOC) $(ASCIIDOC_EXTRA) -b docbook -d book -o $@+ $< && \
+	mv $@+ $@
 
 technical/api-index.txt: technical/api-index-skel.txt \
 	technical/api-index.sh $(patsubst %,%.txt,$(API_DOCS))
@@ -278,7 +280,9 @@ XSLT = docbook.xsl
 XSLTOPTS = --xinclude --stringparam html.stylesheet docbook-xsl.css
 
 user-manual.html: user-manual.xml
-	$(QUIET_XSLTPROC)xsltproc $(XSLTOPTS) -o $@ $(XSLT) $<
+	$(QUIET_XSLTPROC)$(RM) $@+ $@ && \
+	xsltproc $(XSLTOPTS) -o $@+ $(XSLT) $< && \
+	mv $@+ $@
 
 git.info: user-manual.texi
 	$(QUIET_MAKEINFO)$(MAKEINFO) --no-split -o $@ user-manual.texi
-- 
1.7.1.rc1