build-sys: make building of index.html fail sensibly

diff --git a/Makefile.am b/Makefile.am
index a48e05bd8750c0ada0feed7f8594b40a6872fca3..cf911a0fe4b818c6723d6c51869311ebbb175bd8 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -668,8 +668,8 @@ noinst_DATA += \
 CLEANFILES += \
        man/index.html
 
-man/index.html: $(XML_FILES)
-       $(AM_V_GEN)$(PYTHON) $(top_srcdir)/make-man-index.py $(XML_FILES) > $@
+man/index.html: $(XML_FILES) $(top_srcdir)/make-man-index.py
+       $(AM_V_GEN)$(PYTHON) $(top_srcdir)/make-man-index.py $(XML_FILES) > $@ || rm $@
 endif
 
 endif