python: Fix "make distcheck" error on version.py.

The generated version.py has to go in the srcdir and has to be regenerated
based on config.status, which breaks "make distcheck" because it
write-protects the srcdir.  However, the contents of version.py only change
when the version number changes, so we can just "touch" it when it doesn't
really need to change.

The same pattern is used elsewhere in the tree for other files in the same
situation, e.g. the various RPM spec files.

Reported-by: Chris Wright <chrisw@sous-sol.org>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/python/automake.mk b/python/automake.mk
index 96720421075c44763dd9378f659f3210e6829416..447c08fc6f6c5f1c7d4a2f5f302659754f4656d0 100644 (file)
--- a/python/automake.mk
+++ b/python/automake.mk
@@ -62,10 +62,10 @@ ovs-uninstall-local:
 
 ALL_LOCAL += $(srcdir)/python/ovs/version.py
 $(srcdir)/python/ovs/version.py: config.status
-       $(ro_shell) > $@.tmp
-       echo 'VERSION = "$(VERSION)"' >> $@.tmp
+       $(ro_shell) > $(@F).tmp
+       echo 'VERSION = "$(VERSION)"' >> $(@F).tmp
        if [ "$(BUILDNR)" != "0" ]; \
-           then echo 'BUILDNR = "+build$(BUILDNR)"' >> $@.tmp; \
-           else echo 'BUILDNR = ""' >> $@.tmp; \
-       fi;
-       mv $@.tmp $@
+           then echo 'BUILDNR = "+build$(BUILDNR)"' >> $(@F).tmp; \
+           else echo 'BUILDNR = ""' >> $(@F).tmp; \
+       fi
+       if cmp -s $(@F).tmp $@; then touch $@; rm $(@F).tmp; else mv $(@F).tmp $@; fi