Make it possible to override the binary version

debian/rules

@@ -7,5 +7,12 @@ VMODDIR = $(shell PKG_CONFIG_PATH="$(VARNISHSRC)" pkg-config --variable=vmoddir
 override_dh_auto_configure:
 	dh_auto_configure -- VMODDIR="$(VMODDIR)" VARNISHSRC="$(VARNISHSRC)"
 
+override_dh_gencontrol:
+	if [ -n "$$DEBIAN_OVERRIDE_BINARY_VERSION" ]; then \
+		dh_gencontrol -- -v$$DEBIAN_OVERRIDE_BINARY_VERSION; \
+	else \
+		dh_gencontrol ; \
+	fi
+
 %:
 	dh $@