--- a/make/Images.gmk	Mon Nov 28 10:13:18 2016 +0100
+++ b/make/Images.gmk	Mon Nov 28 15:19:08 2016 +0100
@@ -100,7 +100,8 @@
       $(CAT) $(SOURCE_REVISION_TRACKER) ; \
     fi)
 
-$(BASE_RELEASE_FILE): $(INFO_FILE_VARDEPS) $(SOURCE_REVISION_TRACKER)
+# The SOURCE_REVISION_TRACKER file may not exist. Only depend on it if it does.
+$(BASE_RELEASE_FILE): $(INFO_FILE_VARDEPS) $(wildcard $(SOURCE_REVISION_TRACKER))
 	$(info-file)
 
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