Add a workaround for SOURCE_PACKAGE

identify_build_type expects identify_sourcefile to always set
SOURCE_PACKAGE, set it to "*" in this code path. As it is used as a glob
pattern later, this works good enough for now.

scripts/build-and-provide-package

@@ -132,6 +132,7 @@ identify_sourcefile() {
     esac
     p="$(basename $sourcefile .dsc)"
     newest_version="${p#*_}"
+    SOURCE_PACKAGE="*" # FIXME: SOURCE_PACKAGE is used by identify_build_type
   else
     sources="unset"
     echo "*** Identifying newest package version ***"