Don't copy original dsc sources if OBS-DCH-RELEASE set (openSUSE#992)

In that case modified versions will have been generated as part of the
build output. So this avoids coping out two dsc sources, which can cause
issues for the source service and schedular trigger dependency rebuilds,
or publish hook publishing .dsc source package.

This has happend since the merge of d995de1 dsc_move_build_result() will
copy out both original and new one generated .dsc that is list listed in
the .changes files. The .changes files list all the modified sources as
well as the packages so can be consider definitive.

Closes: 928

Author: nickbroon

build-recipe-dsc

@@ -197,7 +197,7 @@ dsc_move_build_result() {
 	mv "$changes" "$BUILD_ROOT/$TOPDIR/DEBS"
     done
 
-    if test "$RECIPEFILE" != "debian/control" -a "$RECIPEFILE" != "debian.control" ; then
+    if test "$RECIPEFILE" != "debian/control" -a "$RECIPEFILE" != "debian.control" -a -z "$OBS_DCH_RELEASE" ; then
 	# link used sources over to DEB directory
 	ln $BUILD_ROOT/$DEB_SOURCEDIR/$DEB_DSCFILE $BUILD_ROOT/$TOPDIR/DEBS/
 	while read f ; do