From: Chris Lamb <lamby@debian.org>
Date: Wed, 6 Jan 2016 11:23:26 +0000
Subject: SOURCE_DATE_EPOCH

---
 src/mkreleasehdr.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/mkreleasehdr.sh b/src/mkreleasehdr.sh
index 1ae9588..e6d558b 100755
--- a/src/mkreleasehdr.sh
+++ b/src/mkreleasehdr.sh
@@ -2,6 +2,9 @@
 GIT_SHA1=`(git show-ref --head --hash=8 2> /dev/null || echo 00000000) | head -n1`
 GIT_DIRTY=`git diff --no-ext-diff 2> /dev/null | wc -l`
 BUILD_ID=`uname -n`"-"`date +%s`
+if [ -n "$SOURCE_DATE_EPOCH" ]; then
+  BUILD_ID=$(date -u -d "@$SOURCE_DATE_EPOCH" +%s 2>/dev/null || date -u -r "$SOURCE_DATE_EPOCH" +%s 2>/dev/null || date -u %s)
+fi
 test -f release.h || touch release.h
 (cat release.h | grep SHA1 | grep $GIT_SHA1) && \
 (cat release.h | grep DIRTY | grep $GIT_DIRTY) && exit 0 # Already up-to-date