[PATCH 1/3] make deb_add_changelog idempotent

[Felix Moessbauer <felix.moessbauer@siemens.com>]

Previously, the deb_add_changelog function considered an auto-generated
changelog as a base to add changes on top. This behavior is not
idempontent on subsequent invocations of the function (e.g. on partial
rebuilds). This lead to both reproducability issues, as well as unclean
changelog files having multiple "generated by ISAR" entries.

This patch changes this implementation in a way to always create a
(possibly empty) orig changelog on the first invocation. On subequent
invocations, the orig changelog is only considered as provided by the
user, if it is not empty.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/debianize.bbclass | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/meta/classes/debianize.bbclass b/meta/classes/debianize.bbclass
index d125256..34347b5 100644
--- a/meta/classes/debianize.bbclass
+++ b/meta/classes/debianize.bbclass
@@ -15,7 +15,9 @@ MAINTAINER ??= "Unknown maintainer <unknown@example.com>"
 deb_add_changelog() {
 	changelog_v="${CHANGELOG_V}"
 	timestamp=0
-	if [ -f ${S}/debian/changelog ]; then
+	# we have a changelog and that is not autogenerated
+	# (when autogenerated, changelog.orig is empty)
+	if [ -f ${S}/debian/changelog ] && [ -s ${WORKDIR}/changelog.orig ]; then
 		if [ ! -f ${WORKDIR}/changelog.orig ]; then
 			cp ${S}/debian/changelog ${WORKDIR}/changelog.orig
 		fi
@@ -34,10 +36,12 @@ ${PN} (${changelog_v}) UNRELEASED; urgency=low
 
  -- ${MAINTAINER}  ${date}
 EOF
-	if [ -f ${WORKDIR}/changelog.orig ]; then
-		# prepend our entry to the original changelog
-		echo >> ${S}/debian/changelog
-		cat ${WORKDIR}/changelog.orig >> ${S}/debian/changelog
+	# ensure that we always start with the orig version of the
+	# changelog on repeated invocations (e.g. on partial rebuilds)
+	touch ${WORKDIR}/changelog.orig
+	# prepend our entry to the original changelog
+	echo >> ${S}/debian/changelog
+	cat ${WORKDIR}/changelog.orig >> ${S}/debian/changelog
 	fi
 
 	if [ -f ${WORKDIR}/changelog ]; then
-- 
2.34.1