[PATCH v2 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 | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/meta/classes/debianize.bbclass b/meta/classes/debianize.bbclass
index d125256..ca7b520 100644
--- a/meta/classes/debianize.bbclass
+++ b/meta/classes/debianize.bbclass
@@ -19,11 +19,14 @@ deb_add_changelog() {
 		if [ ! -f ${WORKDIR}/changelog.orig ]; then
 			cp ${S}/debian/changelog ${WORKDIR}/changelog.orig
 		fi
-		orig_version=$(dpkg-parsechangelog -l ${WORKDIR}/changelog.orig -S Version)
-		changelog_v=$(echo "${changelog_v}" | sed 's/<orig-version>/'${orig_version}'/')
-		orig_date=$(dpkg-parsechangelog -l ${WORKDIR}/changelog.orig -S Date)
-		orig_seconds=$(date --date="${orig_date}" +'%s')
-		timestamp=$(expr ${orig_seconds} + 42)
+		# we have a non auto-generated original changelog
+		if [ -s ${WORKDIR}/changelog.orig ]; then
+			orig_version=$(dpkg-parsechangelog -l ${WORKDIR}/changelog.orig -S Version)
+			changelog_v=$(echo "${changelog_v}" | sed 's/<orig-version>/'${orig_version}'/')
+			orig_date=$(dpkg-parsechangelog -l ${WORKDIR}/changelog.orig -S Date)
+			orig_seconds=$(date --date="${orig_date}" +'%s')
+			timestamp=$(expr ${orig_seconds} + 42)
+		fi
 	fi
 
 	date=$(LANG=C date -R -d @${timestamp})
@@ -34,7 +37,10 @@ ${PN} (${changelog_v}) UNRELEASED; urgency=low
 
  -- ${MAINTAINER}  ${date}
 EOF
-	if [ -f ${WORKDIR}/changelog.orig ]; then
+	# ensure that we always start with the orig version of the
+	# changelog on repeated invocations (e.g. on partial rebuilds)
+	touch ${WORKDIR}/changelog.orig
+	if [ -s ${WORKDIR}/changelog.orig ]; then
 		# prepend our entry to the original changelog
 		echo >> ${S}/debian/changelog
 		cat ${WORKDIR}/changelog.orig >> ${S}/debian/changelog
-- 
2.34.1